Fixing wavy Hull

[Big Guns]

Anybody have any ideas as to straightening large flat surfaces on scratchbuilt hulls?...I'm getting some waves and dips as I'm planking the hull.

Don't want to use filler (i.e. Bondo) that will crack and peel off with time.

[les]

I'm thinking your using wood. How about sheets of veneer?

[Big Guns]

Hey les,

Do you mean to plank the hull or to repair it?

I've thought of using larger sheets of 1/8 plywood..(that's what I'm using to cover frames)..and it works on the flat areas but to get all the different contours and shapes of the old BB hulls the only way I can do it is to use separate planks which tend to get a bit wavy when you have 6 to 8 inches between frames.

[les]

Use plywood between the frames and if there are waves, use sheet veneer to build it up. Where's Ron when you really need him????

[Big Guns]

Sounds like a workable idea...will probaly have to wait 'till after I resin the hull and then fill the low spots/waves...Thanks Les.

[ARH]

Sorry Les I was having my dinner,

The problem lies with the planks , with the shape of the hull as you start to curve the planks they want to twist, what you have to do is taper the plank to half its width, so if it starts off at an inch at one end the other end should be 1/2 inch , this then lets it twist more easily, also you should glue each plank to one another , pin to frames and leave to set, do some on the other side.
Have a look at the next to last picture I posted on IRON DUKE and you will see what I mean, have a look at all the photo,s I think there,s 10 , it should help, the thing is you have to take your time, get it wrong at this stage and its all wrong, ARH

[Big Guns]

Thanks Ron,

I'm kind of working it like you're stating as far as gluing each plank together, however instead of just pinning it I'm actually attaching them with small wire nails that will be covered over later....this hull shape has so many twists and turns the glue alone will not hold them on.

Also I'm trying to run the planks as straight as possible, as I do run into gaps I fill them with ground down planks to keep them flowing as straight as possible but still get some waves....will try to get some pics uploaded in the next few days, you may be able to see what I mean.

[ARH]

Hi BIG GUNS, Yes its o/k to pin them because its ply, its a bit harder than balsa so it grabs them to the ribs, balsa you have to pin and let the glue dry , then take them out, , if you have a few hollows it will not matter if you are going to cover it, the planks are only a rough surface that lets you get the matting and filla to a final finish. ARH

[Big Guns]

Hi BIG GUNS, Yes its o/k to pin them because its ply, its a bit harder than balsa so it grabs them to the ribs, balsa you have to pin and let the glue dry , then take them out, , if you have a few hollows it will not matter if you are going to cover it, the planks are only a rough surface that lets you get the matting and filla to a final finish. ARH

Ron, with that you've brought up a subject I was going to ask you about anyway....If I use matting and resin on the outside of the hull I'm afraid i will loose most of my contours and details, was thinking on using the matting on the inside and just coat the outside with resin....what do you think?

[zach b]

Big Guns with the size model you are working you might want to look at the way small boat builders plank their hulls. Are you familiar with cold molding?

[Big Guns]

Hey Zach.

Don't have a clue as to what cold molding is...any enlightenment would be appreciated.

[ARH]

Hi BIG GUNS, Yes its o/k to pin them because its ply, its a bit harder than balsa so it grabs them to the ribs, balsa you have to pin and let the glue dry , then take them out, , if you have a few hollows it will not matter if you are going to cover it, the planks are only a rough surface that lets you get the matting and filla to a final finish. ARH

Ron, with that you've brought up a subject I was going to ask you about anyway....If I use matting and resin on the outside of the hull I'm afraid i will loose most of my contours and details, was thinking on using the matting on the inside and just coat the outside with resin....what do you think?

Hi I usualy resin the inside and use a very thin fibra matting on the outside fixed on with resin applied with a brush, when hard I apply my resin paste thinly, the matting stops the planks from cracking and the paste adheres better, then sand to shape with a finish like a car body, undercoat , and final finish paint, ARH

[zach b]

Cold molding is a technique many boat builders use today. You use thin plywood as planking setting it up diagonally from the keel, then glass it over. The neat thing is about cold molding is you can pop the shell off the station molding and do without the bulkheads and frames. Not only that but the hull is quite stiff with just stringers and a keel. There is allot more to of coarse, but you get the idea of it.

[Raipier6]

Hey there Helge

This maybe a little late, but when I get waves or a dip in my hulls I use light wieght spakeling. I use it like bondo of course its much lighter so I dont have to worry about the wieght of it causing a list. Anyway I hope it helps a little


Jack