drawing how to

[ernest2]

hi! i need help!!
does anybody know if there's a formula or something like it, that you'll use if you convert the side drawing of a boat in a flat drawing?
i make a design of my own boat, and i have a problem plotting the bottom hull into a correct drawing. i want to sheet the bottom in one piece plywood. the way i did it the first time was trace the bottom lines in a tracing paper to get the exact curves, but that wanst so good, and not accurate.
thanks for anyhelp. i will try to post a drawing when i can so that you may understand better what i meant.
thanks again.
ernest

heres a picture. what i meant was how can i draw the bottom sheeting of the boat based on the side drawing? i cant just trace the plan because it will not fit right?

[Aerominded]

Ernest, from the side view, measure the actual length of the bottom line of the drawing to get the length of that panel, which is actually longer than the boat. Based on the shading in the side view it also looks like you have a slight V bottom on your design- this also makes the bottom panel actually wider than it appears in flat drawings- you may have to draw a front/rear view to capture that dimension- Or, if you like math, you can use the good ole pythagorean therom, A squared + B squared = C squared where 'A' is the drawn width of a particular station from your top view, 'B' is the drawn elevation from the keel to the chine in your side view and 'C' is the actual width of the panel at that particular station. you have all the data you need to do either method using the two views you have. If it is a flat bottomed boat, measure the actual distance between the stations along the bottom line (which will be different as the hull curves up) mark these positions on your panel drawing and measure/mark the widths at each station using your top view. Actually, you will need to do this step too if it is a V bottom. I hope this helps! :)

[CG Bob]

You're right that you can't trace the bottom sheeting from the plan; if you do it will be too short from bow to stern.

The distance along the keel is how long your bottom sheet need to be. Make a template out of some thin (1/32" inch thick) aircraft plywood, posterboard, or cardboard (like on the back of a big desk calender). Tape your template material to the boat framework, transom, and keel; keep the template material tight along the keel. Now you can trace the outline along the chine or turn of the bilge (outer edge of frames). Remove the template from the boat and cut along the lines you made. Test fit the template on both sides of the hull. Lay the template on your hull sheeting material, trace the edge, and cut it out.

[martin richards]

You'' also find, using CG bob's method that the line of the panel forming the keel is not straight, but tapers slightly (on your plan) at the bow.

[ernest2]

thanks for those infos!!! i think its the best way and the simpliest way to do it then.
one more question, instead of cutting and finding ways to lighten the weight of my boat, i decided to make a new one out of fiberglass. i will use the exisiting hull as the plug. now i dont know how many layers of fiberglass cloth i will lay to make a good strong hull. i will be using 6oz cloth. the boat is a gasser airboat 43" x 24"
thanks!!

[martin richards]

Even on an airboat, I'd be happier with at least three perhaps four layers of 6 oz. cloth. Maybe 2/3 if you were laminating over an exp. polystyrene core.

[ernest2]

well i have already laid two layers of 6oz cloth and i think its still flimsy. i think youre right, maybe 3 or 4. and i will still add frames into it after i take it of my so called mold. i am not going to put any foam into it anymore, my original boat is made of 1/8 ply over foam and its heavy. i already take most of the inside and still weighs 4.75kgs. thats about 10.5lbs and my engine and mount weighs 4.25kgs (9.5lbs) my boat totals about 9.5kgs (21lbs) thats why its a bit slow of take off.