MM337 Thorneycroft MTB Model Boat Plan

cheddarman Opening post 2 years ago 14

MM337 Thorneycroft MTB Model Boat Plan

Has anybody built this recently? Just got the plans so any advice/help will be much appreciated.
At 86 it's years since I built a model!!

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Fred Bronze
Commander2 years ago
Hi Cheddarman
I have just come across this build, I did make this boat back in 1970 and run it I/C, like Roy said it had to be made strong for the starting of the motor.
If I remember right the hull was to be a double diagonal plank and the deck was a flash deck with the planks at a 45 degree to the central line.
The maine areament can be got from Battlecraft
Fred
https://www.battlecrafts.com
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roycv Bronze
Fleet Admiral2 years ago
Sorry did not read the title!!! MM337 a very old plan!

This is only a guess but models of this era were built over strongly as they had to stand up to being gripped tightly between the knees to start the i/c engine.

You might want to review the strength of and weight and size of materials used.
I have just passed on a model not built by me but similar which is very heavy due to the above.

It will not plane with a powerful electric motor as it is too heavy to get the hull up, and part out of the water.

Roy
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cheddarman #2 of 11 2 years ago 14

Plan Number

Royce - The only number on the plan is 337A/B

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cheddarman #3 of 11 2 years ago 14

Thanks

Thanks royce, good point! I can't quite work out where the individual sides are on the plan, nor the deck? It's not very clear at all.
I will probably make a lot of the non loaded bits out of balsa to get the weight down!

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roycv Bronze
Fleet Admiral2 years ago
I was thinking about a boat I am building now. All wood should be prepared with a sealing coat of varnish rubbed down wet and dry.

This is so that no visible wood has to be rubbed down in situ. You can paint or spray it but the wood surface is already prepared.

When deck in place and if you planked or have bare wood put varnish on with a piece of rag wrapped around a finger. This puts on a thin layer and does not look thick or puddled and does not have brush marks.

If you glue down pre-painted items, if necessary mask off around the join so that glue does not mark the surface.

You might not like this bit! I do not solidly glue my prop tube in place, I use bathroom sealant. You can still use filler to smooth the exit point.

When you set up the drive train i.e. motor coupling and prop shaft and line them up.
I then run the motor on a low voltage battery and adjust all for the best low friction connection. Let it all run until the connection is secure.

If using a brushed motor, if you have it right, you should feel the 'cogging' of the electric motor when turning the propeller.
Roy
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roycv Bronze
Fleet Admiral2 years ago
Hi, there is usually a rubbing strip around the edge of the hull. This is the outer line. The next line in is the edge of the deck after the sides have been attached.

The frames are inside this line as this is where the sides and bottom are attached. Most modellers will assemble the frames and keel pieces and the stringers to form a 3D object. Be very careful to make this dead square.

The keel if having a prop tube is cut before assembly the prop tube space is allowed for and cut out. Then doublers for each side to retain its shape, check against the plan.

You might find it easier to use 3 inch wide hard balsa to edge-plank against the keel. It saves getting a curved skin to fit.

However, before doing this, work out where the bottom panels will touch the keel and place a 1/8th square strip along this line allowing for the finished edge.
This gives a better glue line for the planks etc. By the way nobody nails wood in place these days!

As it is a warship, it will all be greys of varying shades. So the rubbing strip can be attached early on.

Hope this helps.
Roy
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cheddarman #4 of 11 2 years ago 14

reply to roycv.

I find this forum very confusing, how to reply to a specific post and why doesn't the latest post appear at the top?

Any way, many thanks roycv for your most helpful and informative post.

So, complete the 3D model from the formers, crutches (the formers sit on these) and keel, great.

How does one normally transfer (for example) the deck outline from the drawing to the plywood sheet? I was thinking of using carbon paper? I could of course cut out the profile from the plan and stick it onto the deck ply?

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PeterL3
Petty Officer 1st Class2 years ago
Try baking paper come,s in a roll and you can trace what you want then cut out and use as template good luck pete ❄️❄️❄️
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roycv Bronze
Fleet Admiral2 years ago
I would draw round the upturned boat approximately and cut this out. See if it is the same size as the plan!

Plot where the holes need to be cut in the deck, but do not cut.
See what access you have because before that I would have the drive train in place in the hull.

Positions for rudder servo and esc and battery. I make balsa 'side panel boxes to put them in. Make sure you can get to them. Have a think about balance too.

Think about ease of changing battery and also turning on and off of electronics. Are you aware that modern ESC's have a BEC in them?

The switch on the esc will do, but hide it as prominent switches are not good.

You might find a deck item that can be moved or removed with the switch underneath.

Clamp deck to the hull and sand around the edges to fit.

Then if the outlined holes for access still look square and OK cut, otherwise 'adjust' positions.

Make coamings available in the deck for super structure to be mounted on.

You can then glue the deck down to the frames. I use scrap wood on the deck where the clamps go so you do not get a 'wavy deck line'.
When dry, you can then sand around the hull to fit.

Cut out S/S shapes, I then put cling film over the coamings and then stick the s/s together but mounted over the cling film.

The glue will not stick to the cling film and when finished will be a nice fit.

Some things need painting before mounting, so consider how easy some items are to paint if glued in position.

How are we doing?

Roy
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cheddarman #5 of 11 2 years ago 14

another reply.

Again, many thanks for all your very detailed help. I am copying them and posting them in Pages document so I don't have to navigate the forum page!🤣

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cheddarman #6 of 11 2 years ago 14

compound bends

Almost ready to start applying the plywood sides so wondering which is the best way to go, especially at the bow where a compound bend is required to fit the frame profile.
Can one soak the plywood to make it more flexible? I'm only using 0.8mm plywood.

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cheddarman #7 of 11 2 years ago 14

Getting there......

A few pictures of progress to date. Just a few finishing touches and t'will be time for sea trials!

This 86yo is quite chuffed!!

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cheddarman #8 of 11 2 years ago 14

Sea trials!

Sea trials, well canal actually. Sure can go FAST! Drove the dog mad but not bad for a first outing.
I'm going to put a breakwater on the bow area as I got splashes going into the hatch. Must also make the hatch more secure as it came up a bit probably during a miss judged high speed turn!!
Think some small magnets in deck and hatch?

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cheddarman #9 of 11 2 years ago 14

Where to sell?

I like building, not playing with them iso my MM337 Thorneycroft MTB Model Boat is going to be sold.
Any suggestions where the best place would be to sell please? I thought I saw somewhere on here asking for boats but can't see it??
Cheers

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2 comments

zooma Bronze
Admiral9 months ago
I am not too sure where the best place to sell your model boat would be cheddarman, but if you have a local model boat club, or any friends that you sail with, that would be the most obvious place to try first.

Local model shops can sometimes also be helpful when selling on your models, but sadly they are becoming quite rare these days, but if you do have one within striking distance, it could be worth a quick call - or even a visit to see if they can help?

Online selling on places like eBay or even a site like this one can generate a lot of interest, but would probably attract more buyers from outside your immediate area, and so you would need to consider how prepared you would be to pack and send your model by carrier...or even consider delivering or meeting the buyer part-way, if they were unable to collect.

Good luck with your sale, your model looks good on the water and goes very well.

Bob.
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zooma Bronze
Admiral9 months ago
Your MTB looks really good on the water cheddarman, and has a nice realistic speed.

Bob.
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cheddarman #10 of 11 9 months ago 14

Painting

Just about finished build and come to hull painting.
I must have done something wrong here. I stupidly painted the raw wood with a Tamya spray. It looked all right but when I added a second, and third and fourth coat, sanding in between, every coat now blisters!!
Should I go back to clean wood and how can one do that please?

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HappyHaggis
Sub-Lieutenant9 months ago
Did you end up sanding her back? Its always a tough one that as you've then got to wait days for it to harden before the time consuming sanding begins. Sometimes if it's going to be underwater I end up leaving it though often it'll continue bugging me so its a full strip back to the start. I had it on a cruise ship build and it was all going perfectly until one blister appeared then a million more. Breaks you're heart
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cheddarman
Petty Officer 2nd Class9 months ago
Managed to get the hull paint sorted so is it now a good idea to give the whole thing a coat of some kind of varnish??
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cheddarman

Petty Officer 2nd Class9 months ago

I have bought some Bartoline TX10 Paint stripper to get back to raw wood. Hope I'll be able to re paint once dried out!!

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MM337 Thorneycroft MTB Model Boat Plan

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