frame integrity or longevity

hi yall
building a boat frame

1. from port to stern are 2 1*4's (keel boards)running 12 feet with a gap of 8 inches between them
2. every two feet are 1*2 primarily used for hall design (semi desplacement)
2a the design - 22.5 degrees angels from the keel boards attached with wood glue and screws to form th sides
2b. underneeth the keel boards from stern to bow im thinking of forming 6 inch high isosolese triangles (with 1*2's also) to flat about 4 feet from the bow. also attached with wood glue and screws.
(i figured to sink the 6 inches and and approximate lol of 11 feet would take approx 350 lbs)
3. then in all the gaps placeing foam sheets then aplyling a fibergalss /resin weave around the frame.
4. the mast foundation with be a 2*4 horizontally connected to the keel boards and a second type of attachemt to the side wall 1*2's figured about 12-15 foot tall with the stays equlaized and attacted to as many points as possible for maximum load bearing potential.

my questions
1. do you thing sailing this frame tear it apart
and 2. do you think the more displaced stern would distroy the fiberglass when turning as it woulb be more prone to keel wihout lifting the somewhat more planing bow design.

Me first boat design, no sailing experience, some boat experience, appropriate anchor rigging experience. cost around 400 dollars without sails.

any comments would be appriciated
thank you

 

It sounds like you need a lot more education in engineering and hydrodynamics then you currently have, before venturing into designing a yacht. Maybe finishing school first and while you're there, pay attention in grammar class too. A presentation requires more then just some lines, ideas and innovation, but the ability to convey them to others. Presently you don't even know the terms, for the structural elements and general boat pieces, you are attempting to design. Again and education, across several areas is the wise path to travel down.

It might be easier to convey your design concerns with a drawing or two, showing the basic dimensional lines and a second with the construction details you have questions with. Most designers start with a set of parameters which established several of the design goals. Typically these would be a target preformance envelop you'd like the boat to preform within, weight and general scantling targets, etc. with these things in mind, you shape the boat to offer the preformance necessary, within weight and strength allotments available, in the material choices you've elected to employ. Slapping in a 2x4 where you think you might need one and 1x2's as you think might be desirable, is the fast way to build an overly heavy boat or conversely may not address the actual load paths involved and produce an inherently weak structure. Generally, we size scantlings to suit the tasks asked of the elements as a whole and separately as parts of an assembly.

This isn't meant as a personal dig at you, but an observation, based on your post here and the description of your project.

 

Why are you designing your own boat? Have you looked to see if someone hasn't designed something you'd like already?

Designing a boat on the fly and without a lot of experience is very frustrating and makes the build drag on for months and you'll end up with a nice piece of crap. Let a designer do all the hard work and just concern yourself with the easy part of putting things together.

 

structurally durable



hi,

Im pretty sure i can build a 12ft boat with managable rocker and somwhat soft chines (refer to question one about semi desplacement and semi planning design). The only problem is iv never been in a 12 ft sailboat with at least a mainsail in 10 to 20 mph winds. the frame finished will probile weight around 15-20 pounds. not sure of the weight with the 3.0 ounce fiberglass weave and foam sheats, probibly around 50-60 lbs for a 12 foot boat. Just wondering from the board experience if 1. the frame with 1*2 (all pine) and 1*4 surrounded with a fiberglass waeve and foam sheats will bend and shift to the point a 400 dollar boat will leak after a few waves and tacks. and 2. about semi desplacement and semi planning design (attachment) if the same problem might occur with tacks jibs 180's drunkn stupers ect... wondering after 50 dollars in investments and a year project (lack of funds) is correct if there might be another course some might take to learn to sail or build there fist boat when structural integrityand weight is concerned.

thank you

 

Nothing personal, but you haven't the remotest understanding of the dynamics and engineering involved, to consider self designing a boat, even a 10' boat. You can play with materials, guess at the amount of sail area, rudder area, wetted surface, centerboard or dagger board location, center of gravity, etc., etc., etc. all you want, but in the end, it will be far easier and the likelihood of success much greater, if you just build from a set of plans. 10' sailboat plans are everywhere and some are free, most very inexpensive. I have a 10' design that's $60 bucks (plans) and guaranteed to float where I say to paint the waterline, not fall apart, row and sail well, using basic skills and cheap materials. All the engineering and hydrodynamic stuff is taken care of, no guessing and hoping it'll all work out in the end. Google around a bit and find a set of plans, then come back and bounce the make and model off us. We can tell you if it's a complete set or just old folly, from a bye gone day (there's quite a few of these floating around).

 

coefficients

hi,

i guess i was trying to get your best estimate of the strenght of a fiberglass/resine hall with the frame mentioned (above) over time with a 15 foot mast and 5 foot boom and if it would be worth your money (if you make about 30 dollars a week). sorry finding coefficients are inately out of my reach and therefore I have no desire of trying to puke them up.

best regards
john

 

But there are cheaper ways to make a boat and why are you trying to design one? You seem to be asking for advice but are too stubborn to actually take any.

 

Anyone notice that while the sentence structure and grammer is say school grade 6 there are some design engineering words intertwined ????

 

Yes, I'd say you're close, I'd say highschool. What if someone were interested in building his own radio and had a copy of Ham Radio to fill in the blanks? Any Jr. High kid can do that

But, you guys can tell I'm much older......LOL

 

bump

bump bump bump bump

 

Nothing personal John, but you have to expect to get tossed under the bus with a drawing like that and specifications as previously stated, particularly the way they were posted. Simply put, we've seen this type of request before and are now making reasonable assumptions, based on your posts.

The best advise for you still stands, buy a set of plans (50 bucks, so get over it) and all the engineering and hydrodynamic crap is sorted out for you.