Hi Chris,

I was joking about the painful hands/wrists/finger etc having anything to do with the gentle art of model boat making (and operating), but it does affect our ability to do it as often or to enjoy to as much as we could do sometimes.

Mine is partly old age and related to previous sporting injuries, as well as the usual "wear and tear" that we all accumulate over the years.

"Arthur" has restricted my finger movement for some time and my two smallest fingers lost all articulation some time ago, but the main annoyance is the pain and I find dropping things get more and more annoying - especially as I cannot grip any small parts to pick them up again - especially annoying when it may have taken quite some time to find them!

Not to worry, I am very much aware the old "adage" - "Use it or Loose it".......so I will keep going and refuse to give in to it.

Bob.

Thanks Bob.

Unlikely to be anything to do with model making etc. as it affects both wrists and hands though the right is worse and as you say diminshed grip strength and less dexterity. Started about 4 weeks ago, one day I was fine and next morning I woke up with the pain, having a blood test on Monday so will see what that shows. It does improve as the day goes on and so some days as I said I can do an hour or so of light modelling.

Chris

Hi Chris,

Sorry to hear you are having problems with painful wrist/hand - maybe it's a model boat related problem?

I had to retire from 1/10 electric car racing last week due to the pain in my hands - I couldn't hold the steer wheel transmitter any longer - it was too painful to continue. I had been running since 6.30pm and did not retire until almost 10pm so I had had a lot of tx time, but none the less, it was very disappointing to have to give in to age related pains!

I also keep dropping things - it seems like I have lost some of the feeling in my fingers as well as the pain and diminished grip strength.

Last night I raced the same car again and did OK, but I am pleased that I sold my trials bikes when I did as I think I would have "come a cropper" if I lost my grip during some of the steep climbs or descents we use in the local stone quarry every week.

Meanwhile the Sprite Plus continues to make some progress - but not at the speed that I would have liked.

Bob.

Up to you of course Bob but this is pretty much a build blog and I'm sure Fireboat could change the title to Sprite Plus. But if you fancy it, then why not.

I don't think it would take long for a reader to realise it's not the original.

I'm not doing much of anything at the moment due to this painful wrist/hand problem though I have managed to do the odd hour or two over the last couple of days on my Fisherman.

Chris

SPRITE PLUS.

Hi Chris,

It was a new challenge and a nice change to make a motor mount that was split into two parts (fore and aft) by a frame/bulkhead/former - as it was not something I had ever encountered before

One of the more enjoyable things about building a new prototype model from a good set of plans is discovering anything new or different that I am not already familiar with as it gives the old "grey matter" something different to think about.

After working-out the best method of making the two halves of the engine mounting platform, it was easy enough, and my fears of failing to provide a flat and level mounting surface across the finished laminated engine mounting plate assembly proved to be unfounded as it all worked out perfectly.

Since my last report I have also added a pair of 6mm thick side "spats" to either side of the completed engine mounting platform to "lock" the already solid laminated assembly together still further.

I am sure that this "belt and braces" idea was totally unnecessary, but it looked good and gave me something to cut-out on the bandsaw when I was waiting for something else to dry on another project I am working on.

Maybe a "build log" for this SPRITE PLUS prototype would be a good idea (?) as there are other interesting blogs on here about the original LesRo Sprite that could become a bit confusing to anyone reading them without knowing that this is NOT the original LesRo Sprite design that we are building.

A summary of how the idea of an enlarged version of the original design was first conceived (and subsequently modified), followed by an illustrated build log through to completion would make an interesting "stand alone" article.

.......and I don't know how to change the title of this blog to "Sprite Plus" so a new build log would take care of this problem quite nicely.

Bob.

Hi Bob

It is unusual for the motor mount to fall within one of the frames but you got over it fine as I'd expect you to! Problem was the number of frames and their positioning for supporting the cabin etc.

Anyway, coming along nicely.

Chris

Sprite Plus.

Before gluing the side plates down onto the baseplate the motor assembly was taken out of the hull and the actual Maxi-coupling that will be used was fitted before the motor was reinserted into the hull.

Once in the hull, the amount of shaft that needs to be exposed on the motor and the prop shaft to give a working clearance was checked along with the depth that these shafts sit into the coupling ends.

The rigid coupling was drilled deeper than the actual flexible coupling to remove any movement when aligning everything solidly, so fitting the actual flexi-coupling that will be used allowed the side cheeks to be slid backwards slightly on the engine bed after any working tolerances were calculated.

Once I was happy with the clearance and the exact amount of shaft that was needed to "bottom-out" the motor shaft and the prop shaft in the Maxxi-coupling, the new position of the side plates was marked on the engine bed.

The motor was removed again and the solid coupling shaft was refitted before the assembly was put back into the hull.

Once in the hull, the side plates of the engine mount were slid back onto the marks and super-glued into position.

When the super-glue had set, the motor was removed from the hull again after it had been unscrewed from the side plates, but still attached to the cast alloy part of the cooling mount.

At this stage the prop shaft inner was pulled out from the hull, and a "flat" was filed onto the end section that will be inserted into the 5mm Maxi-coupling.

The shaft was then reinserted, and a 5mm collar was fitted to stop the shaft sliding out in the unlikely event that it should become detached from the coupling when the boat was out on the water (belt and braces).

The motor plate will be roughed-up a little along each side of the motor mount side plates before an epoxy mix is pushed into the drilled hoes that run along the bottom of the side plates and then formed into a fillet to secure them more permanently onto the baseplate.

Bob.

Sprite Plus.

The glue has set and both halves (front and back) of the motor mounting plate (despite my fears) align perfectly with each other giving a nice flat surface that includes the top edge of the bulkhead (former 4) that crosses the engine bay.

This integrated motor platform that is made up from the front and rear parts bonded onto the sides of the bulkhead and the lower hull skins should give a really good solid engine mount.

A water-cooled alloy motor mount will be bonded onto this flat mounting surface with the motor and the solid coupling still in place to maintain the alignment until the glue dries.

Previously, I have found that the alloy motor mounts that have GRP (or carbon fibre) side plates can be bonded perfectly to a wooden motor plate whilst still in position with a thin superglue!

Once the superglue is run along the edges of the side mounting plates it "wicks" its way between themselves and the wooden baseplate it holds then together firmly enough to be able to unscrew the alloy mount and remove the solid coupling leaving the side plates of the alloy motor mount firmly fixed in the correct position.

I usually add a fillet of Araldite 24 hour epoxy along the inside and outside edges of each of these side plates and ensure that it also flows into the drilled holes that run along the bottom edges to give a really secure fixing.

This method has been used in my high milage restored Rapier (as well as my more recent Remora and Sea Commander builds) and has held firm.

Once this is completed I can get some side skins cut and fitted - I have already made the templates for them from old cereal packets so that should be a much faster process than getting the engine mounting completed.

Bob.

Sprite Plus.

Thanks for your input on the motors Harry - it is appreciated as I know you run your power boats at a decent speed and have a lot of experience with different brushless motors in a variety of model power boats.

The water-cooled alloy motor mount will make it easy for me to try different motors, but I think I will start with the least powerful option and run it on 2C.

The smaller rear half of the motor platform was glued into the hull and now that the glue has been left overnight to dry, I can remove the clamps that held it firmly against the bulkhead (former 4) as it dried.

Good downward pressure was applied by the mounted motor assembly to keep the smaller rear half of the motor platform in place against the lower skins, so it should be nice and solid.

Today I can fit the larger front half of the motor mount using the same method to keep it pressed against the lower skins and to ensure that the two halves of the platform align with each other.

Although I had some concerns about making the engine bed in two separate halves, they have been made nice and chunky and should be solid enough.

Bob.

Hi Zooma

All those motors rev high and even more powerful than the 1450 !!!!
You may have to make some speedway sprint wings to keep the boat on the water.

I would try the 1450 on 2S is only about 10,000 rpm and this will cut the power and torque of the motor down.
I think the 1580 motor would be OK in the 37 Swordsman.

Harry🤞

Hi Harry,

I agree - the Turnigy 3648-1450KV is indeed a beast of a motor, but I am not sure if it would be best suited to the Sprite Plus that I am building at the moment.

The Swordsman 37 that will hopefully be my next project however would be a perfect hull to fit it into, so I have "reserved" it for that boat.

I have some Surpass "in-runner" motors that I bought some years ago when there was an offer on them. I am using one of them in my Sea Commander at the moment, but I bought them in three different types, so I will check to see what I think may be the best size for the Sprite Plus.

Following a check, the three different sizes that I have are:-

3675 -1580KV.
3675 -1900KV.
3675- 2250KV.

All three motors look identical to each other, and if the optional cooling jackets are slid over the outer casings the specification stamp of the motor is completely hidden.

The 3675-2250KV should certainly have some serious "oomph" - even though in-runner motors have less torque than out-runner motors.

The first picture shows the 3675 motor - ready-mounted so it can be easily slipped between the carbon fibre "side spats" when needed for use in the Sprite Plus

The second picture shows the Surpass motor loosely positioned above the Turnigy 3648-1450KV where the size of these two motors can be easily seen for comparison.

Bob.

Hi Zooma
The 3548-1450 is a beast of a motor and are not made any more.
I am using the Surpass Hobby 3542-1450 kv which is rated at 1050 Watts on 4S.
I have one in the Sea Rover but only on 3S and a 42 mm 2 blade prop.
I have a pair of 3542-1250 kv in my Pro Boat PT 109 on 2S because on 3S it was too dam fast .
The props 3blade 37mm.
Harry
🚤

Hi Harry,

The motor shown is the one that I took out of my restored LesRo Rapier - because it was too fast (and fuel hungry) for use on our local club lake in Southport, and only gave me an average of 8 minutes duration per run.

I run this motor with a 2C LiPo battery pack. I tested it with a 3C LiPo battery and its performance was very similar, but is duration was even less - even after testing with slightly smaller propellers to suite the increased revs etc.

The advantage of the water-cooled motor mounts that I always use is that they allow any motor to be fitted or changed very quickly.

The Turnigy 3648-1450 is a superb motor, but it just happened to be fitted in an engine mount that I picked up for use when making and aligning the motor mounting plate for this Sprite Plus.

I don't know what motor I will be using in this boat yet - other than that it will be brushless (!), but it could be an in-runner as I have had one on my bench for several years that is well overdue to be put to work!

Bob.

Hi Zooma

That motor on 4S Lipo with a 40/42mm 2 blade the Sprite will fly !!!
I have the same motor in my Spearfish/Spear and Swordsman.

Sprite Plus. The Two Part Engine Bed.

A mock-up was made to check the way that a two part engine bed could be made into an integrated unit when it was combined with the bulkhead that crossed the engine bay.

We had recently scrapped a large model warehouse that we had been using for some years when we used to run a truck club for Wedico radio control trucks, and this was made from 3/8" plywood.

This wood was about 8.5mm thick (in new money) and since the engine mounting plate was to be split into two parts, I thought that it would be a good idea to recycle some of this plywood to make a really sturdy engine plate on which to fix the engine mount.

Using the underside of the bulkhead templates as a guide, the front and rear halves of the motor plates were cut and shaped from this 8.5mm plywood that was used for the base and the ends, with 4mm plywood sides.

The smaller front half of the motor mounting plate was fitted tightly under the motor mount and bonded into place with J.Perkins Rapid bond PVA.

A new solid coupling was quickly machined on the ML10 as the one that I bought with the matching Powerflex coupling was a sloppy fit and I wanted the motor to be held firmly in exactly the correct position while the first of the engine mounting parts was bonded in place.

After this tight fitting solid coupling was fitted, there was zero movement of the engine and its mount and so the first half of the base was held firmly in place underneath it while a small pair of clamps held it against the bulkhead to keep everything aligned until the glue dried.

Bob.

Sprite Plus - fitting the motor mounting baseplate.

With a brushless motor fitted onto the alloy water-cooled mount and joined to the 5mm prop shaft with a solid coupling, the angle of the motor mount assembly can be clearly seen.

The carbon fibre "side spats" of the water cooled motor mount can be seen to be resting nicely on top of the bulkhead cross member.

As luck would have it, the motor mounting "side spats" sit exactly on top of the bulkhead where is crosses through the middle of the engine bay giving the assembly good support in exactly the right place !

The first picture shows the front of the motor mount sitting nicely on top of the bulkhead. (Frame number 4).

The second picture shows the rear of the motor mount on the other side of Frame number 4..

The third picture shows the position that the motor will have to be mounted - partly in-front and partly behind Frame number 4.

This will necessitate the need to have one part of the motor mounting platform in-front of this bulkhead and the other half behind the bulkhead.

Bob.

Sprite Plus.

Having had a rest over Christmas and New Year from building the Sprite Plus prototype, I thought I would take care of the next step - making and fitting an engine mounting plate.

Once this simple job is finished, the adjustable water-cooled alloy motor mount can be fitted to it before the side skins are cut and fitted.

Having fitted the solid 5mm x 5mm coupling to a brushless motor and then screwing this assembly in-between the carbon "side spats" of the motor mount, I had the precise location for the motor to be fitted after it is clamped onto the end of the 5mm prop shaft.

At this stage, I came across a problem that I have not encountered before in all of my 60 or so years of building and restoring Classic Model Power Boats.

The motor has to be mounted on top of a bulkhead that passes directly across the middle of the engine bay. Usually the engine bay is "open" and free of any bulkheads crossing it to give an "uncluttered" and "open" space to plan and fit any type of motor in the best location.

Although the bulkhead that is fitted across the engine bay has a full cut-out, the base of it still has to be "straddled" by the engine mounting plate.

The combination of the shallow angle of the prop shaft and the position of this bulkhead means that the engine mounting plate will have to be made in two halves - one half in-front of this bulkhead, and the other half behind the bulkhead!

The height of the bulkhead cut-out is only just high enough for the motor mounting sides to rest on.

The 6mm motor mounting plate cannot sit on it as it will be too high, so this bulkhead cross member will also become an integrated part of the engine bed (or engine mounting plate).

The motor plate (or engine bed) has to be "rock solid" in any Classic Model Power Boat so this has given me an interesting problem to resolve.

I could cut away 6mm from the shallow base of the bulkhead to make way for the engine mounting plate, but that would weaken the hull (the bulkhead is not very deep at this point any case) and so I have decided not to do that.

As I work my way through this, I will take some pictures to illustrate the problem as I think my words alone cannot describe the situation well enough.

The enclosed picture shows the shape of the bulkhead that runs across the engine compartment (Former number 4).

Bob.

Hi Ronald,

I just use the closest Former (bulkhead) template to give me the correct shape to cut out at each end of the boat stand and allow for the thickness of the bottom skins.

In the case of the Sprite Plus, the ends of the stand locate part-way between Formers, so I averaged the bottom line (that will fit against the skin) between the Formers that are in front and behind the ends and it worked out perfectly.

A cut-out to clear the prop shaft at the desired location was added so that the hull sits really neatly on the stand.

Once the foam pipe insulation is added to each end of the boat stand it does remove the need to be quite so accurate with the cut shapes - but it is nice to know that mine fit well with the boat in the chosen position on the stand before the foams are added.

Bob.

CAD drawing makes the job so much easier and no eraser ✏️ and pencil marks.

I am in the process of "knocking-up" a basic (very basic) stand to put the Sprite Plus on, because when I am working on it (now that it has the bottom skins fitted) - I cannot hold the hull by its keel in the vice any longer!

My "boat stands" look just like the little wooden orange boxes that used to be seen in the green grocers years ago (anyone remember them?) - except those were probably made out of better wood than I use !

I always use scrap wood to make my boat stands from, which may seem a little bit strange to those that spend hours designing and crafting beautifully elegant stands to sit and display their model boats on (some can be works of art in themselves).

My boat basic boat stands are more likely to get a gravel rash from the car park than to be used to display an elegant model boat - but they are very practical and work well enough in the workshop(shed) or beside the lake when they can also be handy for carrying some basic oddments in that may be needed.

Anyway, I am splitting a length of rough-cut square timber to make a pair of sides for the stand, and some plywood has been gained from our r/c model truck club when the garage unit that had been used to practice reversing manoeuvres in etc became surplus to requirements!

Once the stand is put together I can start to make the parts for a good solid engine mount and get a motor and coupling fitted.

Bob.

Hi Chris - regarding the oilers. They are available in 5 (?) different diameters to fit a variety of prop shaft tube sizes.

The sizes are colour coded (anodised in different colours depending on the diameter of the tube it has to fit).

I even found one to fit the small 4mm stainless steel propshafts from J.Perkins that I have used on my Remora.

These are quite skinny prop-shafts so I was surprised to find that a collar had been made to fit them as I have not seen any others as thin as them.

They are not expensive so I have one of each size to check-fit against any tube I have before fitting it.

Bob.

Excellent!

I haven't seen those oilers before, they look really good.

Chris

Hi Chris,

Here are a few pictures I snapped on my way out this morning to show the trimmed bottom skins with the 5mm Maxishaft fitted and the large rudder post in place too.

I have fitted one of those excellent alloy prop-shaft lubricators. This had to be removed again to slide the tube into the transom and re-fitted once the tube was partly inside the hull before it could be inserted through Former 5 (the engine room firewall).

There was just enough “wiggle room” to twist and slide the shaft tube in the keel after it was smothered in 24hr Araldite to give it a good even coating - and to make sure that the oil-nipple was pointing upwards before the epoxy resin was left to set!

An old S50 propeller was fitted just to check the clearance as this would be the biggest size of propeller that could be used, although an S45 is more likely to be the biggest type that would employed with the out-runner that I have in mind.


The 24 hour Araldite has dried to a sticky feel (cold workshop/shed) but should be hard enough to be cleaned-up when I get back next week and start to make-up the engine bed for the adjustable water cooled alloy mount (exactly as drawn on your plan!).

Bob.

Thanks Bob.

Even though I'm experienced on the drawing board it is so much better producing drawings (not CAD in my case) on the computer using a drawing program as you can line things up very accurately and zoom in if required. And of course for frames and other symmetrical parts you only have to draw half and then copy and flip to produce a perfectly symmetrical shape.

And ensuring that things fit together is why I always draw everything even if it is only the frames are required as was the case with the original Stiletto drawing. Mix and matching between a paper drawing (which might be distorted due to folding and age etc. and a new drawing for the frames invariably leads to issues, though as you say they can be corrected during the build - but it is best to try and get it as right as you can from the start.

For some parts though, like the vee shaped front cabin windows, it's best to just make them rather than spend a lot of time drawing them as it is very easy to get them wrong because of all the angles at connections. This was the case with my Faun build where the cabin sides aren't parallel and being in mahogany I didn't want to use any filler! If I ever did any full drawings I think I'd make some parts first and measure them for the drawing! 🤔

Its all thanks to your good drawings Chris 👍

I have not had to change, modify, or recut any parts as everything fitted correctly and aligned nicely.

The acid test for me is when the stringers are being fitted and the lines can be given the "Mark1 eyeball test" (not so easy when wearing vari-focal lens!).

All the lines flow nicely with no lumps or bumps that needed correcting, and this is not always the case - even with some of the better known model boat kits!

Take a good look at any old Sea Commander or Sea Queen the next time you see one (there are plenty of them about). Many have deck lines that do not flow, but resemble the rise and fall of a big dipper (yes I exaggerate - but you get the point!).

Some are much worse than others and some of the kit builders have taken the time to make "corrections" before the stringers are fitted to make sure that the deck lines "flow" nicely - your drawings produce parts that needed no corrections to "fit and flow" nicely.

I have rushed through this build a little (I am usually a slow fussy builder) as I have not had so much time at home this year, so when I am home there are a lot of other things that need "catching-up" with (home and garden) that can build up when you are away, so this build has had to be squeezed in-between everything else.

With everything fitting so well, it has been a very enjoyable and easy build that I have enjoyed working on, and when I get back again I look forward to making some more progress.

Bob.

That's good to hear. As Will says you're making great progress.

Hi Chris,

The bottom skins were probably the easiest that I have ever fitted, so no problems as they almost fell-on and fitted themselves with very little effort.

Using the cereal packet card as the template gives a very similar "wrap" to that of the plywood skins and so I was able to cut them much closer to the final shape than I would usually do.

I marked the "slot" position where the shaft will pass though and filed away a little in that area to make it easy to find and open up after the adhesive on the skins had dried - likewise the square cut-out for the rudder post.

The small amount of excess bottom skin that I had left was cut away this morning with the Tamiya razor saw and sanded back with a 280mm long Wedge PermaGrit ready to take the side skins.

The slot for the prop-shaft was opened out fully where the skin had partially covered it and the square cut-out for the rudder shaft was drilled with an 8mm drill.

A "large" size rudder was fitted and the 5mm Maxishaft (with an S50 propeller fitted) was inserted to check the angle against the plan and the clearance to the underside of the hull.

The prop shaft the was roughed-up with a corse round file where it passed through the hull and an alloy oiling clamp was fitted before using 24hour Araldite to bond the prop shaft in place.

The hull has been left to dry overnight with an elastic band (technical clamp!) wrapped around it and the hull to hold the shaft firmly in position while the slow drying adhesive sets - could be even longer than usual in my cold workshop(shed).

Bob.

I thought they'd be some difficulty with the skins at the bow as they curve up and also transition from the angle of the second frame to the flat of the first frame but it appears there was no problem with that then.

I thought I had a lot of clamps! 😁

Fair play Bob, you're making great progress and flying through this build 😀👍

As Chris says, you'll have your Sprite on the water in no time.

Will

Both the bottom skins were cut out this evening - this probably took less than 10 minutes to cut the pair using the Tamiya razor saw.

The Sea Commander stand came in handy to hold the hull during this stage of the construction! Once the bottom skins are fitted and trimmed I will need to make a stand for the Sprite Plus as I want to use the back seat of the car again shortly (where the Sea Commander is currently "resting"). 🤣

Plenty of glue was used on the framework before aligning the skins, it was spread more evenly just after the first picture using an old lolly stick that also scooped up the 'dribbles" and put them back on the framework too!

Once checked they were glued onto the hull using Rapid PVA and sharp brass nails to hold it in place with clamps around the outer edges.

Tomorrow the nails can be removed (some will have their heads cut off and be driven in give a mechanical fix to give double security with the glue bond).

It is always important to glue both bottom skins at the same time to prevent any possibility of warping and/or twisting, so I was stuck out in the shed for a couple of hours until this was completed.

Tomorrow I can trim the excess from the bottom skins and think about fitting the prop shaft and aligning it with a suitable motor and mount assembly before the side skins are fitted later.

Bob.

You are making really good progress Bob. It won't be too long before it's on the water!

The bottom and sides of the boat have been shaped to flow across the bulkhead profiles and are now ready to be skinned.

The extended cabin front parts between Formers 2 and 3 were extended down far enough to also be bonded to the bottom skins and were profiled along with any else that will touch the skins.

Bottom skin shapes and side skin shapes were made indoors on the nice warm kitchen table tonight as the evening meal was being prepared (!).

It only took a few minutes with a couple of cereal packets and a roll of making tape to determine the shapes and cut the templates out.

Once the templates were cut, they were reversed and laid on the opposite side of the upturned hull to check the fit again and to confirm that both sides are exactly the same shape and show no twist or distortion.

Both sides fitted the same, so the hull "checks-out" as being nice and symmetrical which is always nice to see.

The pattern will be drawn onto some ply skins and cut out with my Tamiya razor saw as I have found this to be by far the best tool for the job over the many years that I have been cutting skins out, as it is precise and cuts very neatly with its super fine toothed razor sharp blade.

Bob.

Hi Ed,

Yes, I used to use round blades in my fretsaw and coping saw frames quite a bit and being able to cut in any direction is very handy.

I think they used to be called Abrafiles ?

The blades that I am using in my Hegnar fret saw are very thin and have very fine teeth that cut like a hot knife through butter (but a lot slower!), and even when cutting with these blades the plywood surface can chip lumps off of the top surface layer of the laminate.

I don't think round fret saw blades would help to stop the "surface chipping" on the plywood that I am currently using, I think the wood is poor quality and badly laminated and that is the problem rather than the way it is being cut, but I will see if any are made to fit the Hegnar as they are such a useful blade to have.

Bob.

Bob have you tried round fret saw blades?

Some (empty) cereal packets have been found and are being taped together to make a long enough length of card to use as a template for the bottom skins.

The new plywood skins that have just been delivered are far from being flat - they are very wavy.

If they had been sandwiched in the delivery box between the thicker sheets of plywood that I bought at the same time they may have been a little flatter?

As it was they were placed on the outside of the other sheets of wood with the hardwood strips that I ordered to use for stringers etc and held together with some elastic bands.

I think they will be OK once they are cut and then pinned and glued to the hull frames, but it is another example of the current crop of new wood not being anything like as good when delivered as it used to be just a few years ago.

The 4mm birch plywood is not very good either. When it is being cut, drilled, sanded or filed, the top laminate layers can chip-off giving some ragged edges.

Even the cabin front edges chipped off in places when being cut on the jig saw, and the Hegnar machine uses needle thin fine toothed blades that are not capable of cutting too fast.... or causing any other "user" inflicted damage to the plywood surface.

The wood quality is poor - the laminate layers are not bonded together very well at all and the edge "chips" are something that I have never experienced before in over 65 years of working with plywood!

Not impressed!

Bob.

Hi Chris,

The prototype Sprite Plus that I am building from your drawings is going together well with no problems found.

Other than extending the cabin sides a little further forwards to connect Formers 2 and 3 together I have found nothing that I would change if I were to build another one in the future.

Some scrap 4mm was cut to imitate this cabin exension and does the job well enough with minimum effort or cost.

I added also some scrap 4mm pieces horizontally between Former 2 and 3 to support the lower part of the cabin front and to give a simple base to glue some deck formers onto.

The above small tweaks are the sort of things that I enjoy doing and appreciate that another builder may prefer a different solution.

I quite like the parallel sides to the cabin as it adds to the chunky look of the boat, but when get a bit further it will be easier to see if shaping the cabin sides would have looked better.

Having a nice warm indoor working area must be a real bonus - something I can only dream of ! (I am interested and considering the diesel heater that Ed mentioned on here).

Bob.

When drawing I started off with a breasthook going all the way back to the cabin windows, I should have kept it in!

The sides of the cabin/coaming being parallel don't look too bad really.

Whilst me using the small bedroom as a workroom does have it's drawbacks, at this time of year it has a big plus and with this run of inclement weather I've been able to spend quite a bit of time in there.

Chris

It was a balmy one and a half degrees this afternoon (!), so I popped out into the workshop(shed) after cutting out the window shapes on the fret saw and did a mock-up to see what it would look like on the hull.

There is a lot of final fitting and finishing to be done yet, but the front cabin shape has been decided and the curvature of the deck between it and the bows can now be seen and the formers can be made ready to support the deck skinning in this area.

The elastic bands show the creature of the deck quite well.

I added a 6mm "cover" to the front Former 1 so I have enough thickness of wood to give me the option of sinking a couple of pairs of 5mm threaded inserts into it to allow the future fitment of a soft bows or a "pusher-frame" for its secondary use as a possible recovery launch?

In passing, I have noticed that the quality of the currently available 4mm birch plywood is not as good as it used to be. The wood tends to "chunk" small lumps off of the edges (on the outer laminated layers) when it is being cut or sanded.

The blade on my Hegnar fret saw is VERY thin and has exceptionally fine teeth - and even that chunked some small lumps out of the 4mm birch plywood surface as I was cutting out the window shapes.

The wood will need some extra treatment when I get to the final finishing stage to improve the integrity of the wood. I am not too sure what to use for this yet, but maybe some thin glass fibre resin could be soaked into the wood to help strengthen the bond between the different laters?

Bob.

Hi Ed,

That is a very interesting video - it looks really good.

Still not too sure about having diesel fuel inside my wooden shed, but maybe that is just because I am naturally cautious ?

......I do like the idea though !

Bob.

Bob here is an example
Will take a picture of mine later and post

Hi Ed,

I like the idea of having some heat in my workshop(shed) - especially cheap heat - but how safe would be in my over-crowded wooden shed that is full of wood and quite often sawdust and glues etc?

It probably represents a good example of a tinder-box...........but I would like to be wrong, of course!

Bob.

Bob, last winter I fitted a diesel heater to my workshop/ garage. It’s great and heats the workshop up to 18+ degrees in about 15 to 20 min. Cheep to run as well.

Ed

It is really cold in my unheated workshop(shed) at the moment (-1), so I have not done too much, and the small oddments that I have made and glued together are taking longer to dry than they should!

I have started looking at the front of the cabin and chopped out a pair of front cabin window blanks from some 4mm scrap to make a "mock-up", and I think it is going to look OK with the revised cabin shape..

The original Sprite's cabin had a flat front, but I think this larger size does suit the two part angled cabin front a little better, so I will tidy-up my rough chopped-out parts and use them.

The front under-deck area needs filling-in to further strengthen the bows and to give a solid base for the cabin fronts and the deck formers to sit on.

It is starting to look a bit more like a boat!

Bob.

A pair of bulkhead spacers have now been made from 4mm plywood and fitted between Former 2 and Former 3 to improve its robustness as an occasional potential pusher recovery boat.

These additional spacers are fitted inline with the cabin sides and would be an extended part of them if I should ever build another Sprite Plus.

As separate parts, I have extended them down to the bottom skins position so they can also be glued onto and integrated with the skins when they are fitted later.

A rear deck former (with a central support) was cut and fitted to support the small area of ply skin that will cover it.

The 11" Maxi prop shaft (5mm) has also been dry fitted before the front of the rear well was made and glued between the cabin sides to strengthen and complete this part of the build.

Once glue has dried around this small bulkhead , I will rough-up the outer prop shaft tube where it passes through the keel and use 24hour Araldite to secure it permanently.

My next step will be to take a look at the cabin front and decide what final shape to use and work-out how to fit it to the front deck area that will need to be reinforced to fit the cabin front securely.

Bob.

I found my box of thin black mechanics gloves (to protect the wood!) and fitted a couple of small parts and deck supports across the rear of the cabin sides this afternoon.

The ends of the stringers (where they pass through the transom) were cut off and sanded flush to the surface, and after the whole surface of the transom was sanded smooth a plywood skin was cut to shape and fitted over it and then glued on with RapidFix PVA and held in place with clamps around the edges and brass nails to prevent any "ballooning" in the middle.

When the glue is dry, the heads will be cut off of the brass nails and they will be driven into the surface to give a mechanical fixing to assist the glue bond.

This transom "cover" is something that I like to fit to all my Classic Model Power Boats to give a nice clean finish to the back of the boats, and on the Sprite Plus there are several slots where the deck stringers, chine stringers, ends of the cabin sides and the keel all locate into the transom so they are all covered over nicely to give a nice and secure finish to them all.

The transom cover is fitted before the bottom, side and deck skins so that when they are fitted later they will overlap the edges of the transom cover to give the most durable protection and fit.

Next I need to take a look at the front of the boat and make some supports to reinforce the space between Formers 2 and 3. This will probably take a similar form to having the cabin sides extended to join Former 2, which is something that I would do if I should ever make another Sprite Plus.

Whilst working around the front of the boat I will give some more thought to how I will make and finish the flat pusher bows as I am not convinced that balsa wood would be the best choice for the contact area of a boat that could be used for recovery work.

This is nice project that gets "the old grey matter" working by solving problems and considering the alternative as I go along.

As a matter of interst, this is also the reason why I take on so much restoration work as the problems that often arise are not those that would normally be encountered with a "new build" (such as fuel soaked and rotten wood, poorly glued or fitted parts, twisted hull and banana shaped decks etc .......).

Bob.

Progress on the Sprite Plus prototype has been slowed a little due to my injured thumb.

Every time I bump the end of it, it starts to weep some of that red stuff that tends to stain the wood which is getting to be very annoying!

I will concentrate on some of the smaller parts that need to be cut and fitted and save the bottom skins until I can fit them without staining them!

Bob.

I won't show any pictures of the thumb, but this is the device that chopped a lump out of it !

This is very good sharp clean cutting little plane that made light work of trimming away the keel and the doublers ready to fit the bottom skins.

The small accident was my fault entirely, I was trying to hold the frame of the boat against my chest with the left hand as I was planing it with the right hand and obviously failed to control either the boat or the plane adequately.

Not to worry, most of the woodwork washed up OK with clean cold water and so "alls well the ends well" as they say 🙄

Bob.

Made me wince just thinking about it!
Hopefully it'll heal quickly Bob.

Ouch indeed! 🤕

The Sprite that bites! 😀

Ouch!

With both sets of stringers fitted to the hull, I thought I would start to shape the keel and doublers ready to accept the bottom skins.

After scraping away at the 18mm combined thickness of the full length keel and doublers with my various Permagrit tools, I decided to get the plane out and use that instead.

Progress was much faster and more easily controlled, but the finish was rather too nice and smooth (almost glazed) so I will "rough it up" a bit to allow the Jet Set PVA to penetrate the wood surface more easily before adding any skins.

With a nicely sharpened blade slicing through the wood, I lost concentration for a millisecond and trapped the pad of my thump between the edge of a bulkhead and the approaching plane.

The results were not too pretty and the blood stained some of the wood.

After quickly wrapping some masking tape over the wound to stop the bleeding I sponged the wood with cold water as quickly as possible to clean it as well as I could.

Now with the thumb more professionally covered with a plaster, I will venture back into the workshop (shed) to see how successful I was at cleaning the wood and as soon as it is dry enough (!) I will rough-up the smoothly planed surface ready for the bottom skins to be glued on.

If the wood is still a bit damp, I will start to make some templates for the bottom skins using some old cereal packets taped together to make them long enough.

Bob.