Lapstrake sharpies?

Yes, you can get lapstrake planking to fit around compound curves, both solid lumber and plywood planking. One of the nice things about plywood is the ability to cut really odd shapes and have reasonable cross grain strength, where solid lumber planks would need to be steamed to other wise fit. I can lapstrake a football (American) with plywood or solid lumber, but it would be easier with plywood.

The "universal curve" isn't a new idea. It's commonly referred to as a common curve section. Decks are often done this way for the crown and boats with "arc bottoms" too. Of course it's shape limiting, but can make a fairly bland slab sided hull into a more shapely one, with reasonable ease.

Given a choice, I'll plank a lapstrake with plywood every time. It's not prone to splitting, holds fasteners better then the usually species of softwood used in lapstrake builds. It's tough, you can cut odd shaped garboards without having to hold you jaw just right and used in a glued lap build, about as light a boat as you'd want or could build with any other method.

 

Yes , no cupping or splitting is nice , I would even go to the trouble of capping each plank edge on the exterior .

One question on lining off : Is it best to follow line of flare angle , or do you divide along a vertical line from chine to sheer ?

 

There are a lot of ways to do it, but none are any more "correct" then any other. I've seen them done on the "diagonals" which actually works out fairly well, others very carefully use percentages of the vertical distance at each station, others like myself give the sheer a little extra for looks, then split the vertical distance equally at the stem and from the tune of the bilge up at midship and the transom. Ultimately, you have little choice but to just give yourself a ball park range and then "make them sweet" by eyeball. You have to make allowances for the shape of the boat too. Some places the curves may require smaller width planks, others may permit wider. There's no substitute for a lining batten. In fact, when I design a lapped boat, I line the profile off by hand and scan these into the machine. The computer screen is too small to really see how well a lined off hull actually looks, you have to have it big enough to see. Since I don't have a 36" monitor, I do it by hand.

I'm not sure what this is . . .

 

My question ( lining off ) was specifically for sharpies PAR ,
it`s clear now that it`s actually more art than anything else.

The red line was what I meant by flair angle..

 

Yep, it can be worked out with ratios, percentages, etc., but the real test is if it looks good by eye. The act of lining off is an eyeball thing and one of the testaments to a builders skill.