Hey guys, just a heads-up regarding my Vivacity build; I'm transferring any future comments (and possibly re-writing some of those started here) to the Build-Blog section as I've 'formally' started work on the build, so I suppose that will all but finish this thread.

Can I take this opportunity to thank all of you who have contributed, followed and given feedback regarding my comments and enquiries regarding this build, and I look forward to sharing my progress.

Best regards,

Nick

If you know the outer diameter of your prop shaft tube Nick, it would be better to cut the slot out for it now and add the doublers to retain the keel shape.

I like the way you have pieced the pine together to make best use of the width you have available and the way you have formed the “buttress” at the bow to give it the best support.

Nice work - no stopping you now !

Bob.

Although still waiting on the prop shaft and tube, I decided to go ahead and trace/mark/cut out the pine keel pieces - feels good to finally get this build underway😊. Pieces were placed together over the plan to check fit. Will wait a little longer to see if tube turns up in next few days, but if not, I'll go ahead and glue-up the keel as it is, then cut it to fit the tube and doublers as and when it arrives.
Next job will be to make up the bulkheads, and then a jig of sorts to secure the keel in place for fitting the bulkheads to it while keeping everything square....🤔.
What do you guys do as far as jigging is concerned, if anything?

rgds, Nick

The size of the prop shaft inner and outer may have some influence on whether the 5’’ of prop shaft hanging under the hull needs any support or not.

Nick is planning to use a 5mm inner shaft (at this stage), and I would certainly prefer to support 5 inches of shaft protruding under the hull for a couple of reasons.

The first is purely aesthetic - it will look much nicer and more “finished”, and the second is rather more practical.

If the hull should ever collide with anything solid such as a submerged log or get knocked during transport, a supported shaft of this size is far less lightly to get bent or damaged - or its mounting in the hull disturbed.

Each to their own (as always), but I would certainly support the exposed 5 inches of prop shaft if it were my Vivacity.

Bob.

On my boat the prop is per nick wards but no brass fitting never had a problem with vibrated I have a oiller on the prop tube and the motor is rubber mounted

As Bob says a triangular fillet is common practice with another being a P bracket as I often use.

Thanks for that, Bob. Yes I had thought of it, and now you've said it, it's probably the best compromise, a more elegant solution than what I originally suggested. I could also wrap a band of brass sheet around the end of the tube and bolt it through this skeg for further reinforcement - I did this with the Sprite (see pic). Looking at the shape of the hull, I can only assume the shape suggested on the plan was to improve the steering perhaps? Can't think of any other reason ...

Thanks again for the feedback,

Nick

I don’t like the idea of having an unsupported prop shaft hanging underneath the hull either - especially not 5 inches worth!

My solution would be to fair-in the gap between the underside of the hull and the top of the shaft only.

I use the technique on all of my Classic Model Power Boats to support the prop shaft and to help prevent vibration if the original design does not already include it.

This idea works, and because the underside of the “keel” remains as per the original design there can be no adverse affect on the steering and the prop shaft is supported.

Bob.

The only thing I could possibly think is that the added keel area would somewhat affect turning ability but add straight line stability. Until it's in the water hard to predict. Rudder may need tinkering, maybe kinda sorta?? My 2 cents but I'm no marine engineer 🤔🤞😉😁

Hi all, just a quick update ....and a question.

Firstly, I've started to draw up paper templates (see pic) for the bulk heads, including provision for the 6mm sq. stringers between the chines to support the slightly thinner (1.5mm) ply skins I intend to use.

I also managed to find a very nice piece of 10mm pine from which to cut the keel pieces - very consistent grain, almost dead straight (rare in depot stored pine, I've found - took me a while to find this one, after searching through the whole pile) and completely clear of any knots.

I'm still waiting for the prop tube and shaft, which I believe is meant to be 9.5mm outer diameter, allowing it to fit nicely between pieces of the keel with ply cladding on the outside. However, having looked at the plan, the original design leaves about 5 inches of the prop shaft hanging outside the keel unsupported, which I am not comfortable with, so I have decided to extend the keel piece as shown in the photo ie extending the bottom line all the way to the plane of the tube opening.

Here's my question; do any of you think this will have any kind of adverse affect on the boats performance? It might make the design look more conservative, I suppose, but I don't think performance will suffer, but I could be wrong - your thoughts...?

rgds Nick