Generally speaking, is there a "rule of thumb" as to where beam should be located?

AHhhhhh but on second sober thought you see i have retracted it-- prior to both your posts I thought but you're just too fast-- Why not have fun experimenting after all isn't that what models and test tanks are all about -- Sorry Choppy, that post was bad advise, welcome to the wonderful world of marine trial and errors Geo.

 

Ya Daiquiri--put my foot in my mouth that time-- Spose you guys will never let me live that down--considering i'm about to go to the shop and maybe--just maybe make another small change(stretch it out) in my main keel mold before glassing up on Sat. Boat building is so easy--Boat design, well that will drive one nuts---

 

No apology necessary. You were trying to help me and I appreciate it very much. Thank you for taking time out of your day to reply.

Thanks,
choppy

 

Thanks, have fun mate, curse me later , Na just having fun wit ya, Love building and the puttin the dam things thru their paces---Geo

A yacht is not defined by the vessel but by the care and love of her owner---

 

If any designers on the forum have time would you please comment on post #13.

Thanks in advance for any help,
choppy

 

Re post #13. The maximum pressure is at the bow if the boat is not up on a plane or turning. Where the water is being "pushed back" (bow wave or chine spray in turn) is where the pressure is greatest. When planing in straight line the greatest pressure is at the hull water interface.

I will not be insulted if this post needs some corrective response.

 

Choppy you have been well advised. Buy a set of plans for a proven boat. Believing that you will buy a set of plans and build to get the same result is a huge presumption. The presumption being that you can design a boat as well as a seasoned veteran designer. That is what is called; shooting yourself in the foot. No offense here, but your original question suggests that you may be short of design experience and long on ambition.

You want a go fast, quick to plane, lightweight, proven, small boat....look at some of the hot designs such as Dudly Dix' Paper Tiger.

 

The best location for the Beam is in the liquor cabinet.

 

I second that.

choppy

 

That is one nice sailboat. Thanks for the tip.

Please allow me to ask one question. When you design a sailboat what do you design first (the placement of the mast or the keel?

Thanks,
choppy

 

You ask all the questions that everyone wishes you wouldn't don't you?

For the maximum beam, look at the trend from the mid/late 70s (Laser, 420, 505, LARK, Scorpoin etc.) to the latest and greatest skiffs. The position of maximum beam probably hasn't moved that much, but the hulls have become significantly more prismatic aft of midships. It's the hull-shape below the water that is important, and Bmax is one small part of that. For a planing hull you want to keep the run (buttock lines aft of max depth) as straight as possible, with only a little rocker (again, look at the modern skiffs vs the old boats).

In terms of what you design first, I guess it depends who you ask. I would tend to draw the hull first, and get it to a shape I liked "by eye", then do the hydrostatics to check it floats where it should, tweak, repeat. Once I have a hull-shape that floats, then place the keel, which if ballasted will affect the weights and hydrostats, so go around the loop again. Then find the static trim at heel, and the moment to change trim, ensure these are sensible (i.e. do a quasi-static calc to find running trim ignoring squat), which will require you to have an idea of the rig size. Placing the rig will affect the weights, and getting a reasonable "lead" may require you to move or sweep keel. Do all previous analysis to check. Now you can start to refine the rig design, going round the full loop described a few times. Eventually you'll have a hull, keel, rudder and sail plan which you are happy with. Surprisingly, this doesn't usually take very long. The next bit, designing and drawing the structure is MUCH harder.

Remember, design is not about drawing a pretty boat. It's about making a pretty boat work.

Good luck,

Tim B.

 

Thank you for taking the time to write such an informative reply. I kind of thought that would be the order in which you would build/design a sailboat. I think I have all the information I need now to get started.

Good luck to each and all with your designs,
choppy