Size of frames on 16ft longboat

[tkay11]

I'm trying (no, struggling) to make a 16ft boat for the cutter Sherbourne. I'm basing it on the longboat portrayed in the AOTS Alert, although zu Mondfeld would probably call it a barge rather than a longboat.

 

The method I am using is one of those suggested by zu Mondfeld in his book 'Historic Ship Models': namely, making a male mould from a wood block and then wrapping frames around it -- from which the mould would eventually be removed.

 

In order to do this, I first transferred the plans to Photoshop and traced them, then re-sized to scale (at 1/64) to match the scale of the Sherbourne.

 

Then, using the cross sections and the sheer plan, I made the mould. This I did not find very hard, and quite enjoyable. However, it was from here that my troubles began. Essentially, my problem centres on the frame size.

 

Having had a look at Chuck's longboat builds on this site, I reckoned a frame made of 2mm x 2mm walnut would be ok, thinking I could wrap frames of this round the hull after suitable steaming/heating.

 

However, the moment I started to think about this in detail, I realised that a 2mm frame would dig in substantially at the stern. If you look at the picture below, I have shown the placing of the frames I was thinking of by using black blocks on the diagram which would show me where to cut the template.

 

I taught myself how to use TurboCAD so that I could experiment with different templates for the frames, but all this has shown me is that I still can't figure out how to approach the frames at the stern, notably for the last three frames I show in the picture.

 

Even if I drop my frame size to 1mm x 1mm the frames at the stern would still intrude. I have a feeling I should build a false keel and then work my frames from there, but I'll wait for any advice.

 

Maybe I'm approaching it in the wrong way, but to start with, I'd like advice on the following:

 

1. The rough original size of frames for such a boat. I was thinking maybe 2.5 inches square would look about right, which would translate into 1mm square frames at 1/64 scale.

 

2. Would it be better to develop the framing in a different way?

 

3. Would it be even better to give up trying this as I'm out of my depth and skill level, and just get on with making the boat as suggested in the kit instructions (there is no mention of a ship's boat in the plans or instructions)?

 

I attach photos showing how I made the layers from the waterlines which I then glued together and then shaped with files. This method allowed me to keep a constant eye on the waterlines as the paper was sandwiched between the blocks of MDF (medium density fibreboard -- as it is known in the UK). So if people spot an elementary mistake here as well, then I'd be grateful for correction, as usual!

 

Looking forward to any available wisdom!

 

Tony

 

 

[Jim Lad]

Tony,

 

At a scale of 1/64, the scale frames would be way under 0.5mm in size, if you're looking at scale framing.

 

John

[tkay11]

Oddly, that might make my job much easier! Thanks very much, John, for the info. I have a lot of wood of 0.5mm thickness.

 

Tony

[allanyed]

Tony

The following are the scantlings for a 16 foot cutter found in W.E. May''s book which were taken from Steel, so we are talking about 1800 +/-

 

Floors

Sided 1 1/4"

Moulded at the head 1 1/8"

Moulded at the throat 2"

 

Futtocks

Sided at the heels 1 1/8"

Sided at the heads 7/8"

Moulded at the heads 7/8"

Scarph of the timbers: 1'7"

 

Hope this helps you

 

Allan

[tkay11]

Oh, that's brilliant, Allan. Thank you very much! It accords with John's suggestion of less than 0.5mm.

 

Tony

Edited March 27, 2013 by tkay11