TCHedOff

I am working on a from-scratch wood .12 rigger (to drop my Miss Bud engine into over the winter; and put a .21 in the Miss Bud).

Is there a formula for determing the surface area for front and rear sponsons? I would think there is a weight to surface area ratio, but I havent found anything on the various forums on this subject. How these boat designers deciding on the size... the optimum lengths and widths?

I have the same question on determing the depth of the sponsons....

thanks

Ron Olson

My Feedback: (1)

Actually it is a very good question. At one time I was going to market a .12 'rigger, the Hammerhead .12 . Don't ask the reasons why but we never got it to market. I didn't do the design work, I was only going to do the grunt work on it, assembly, shipping, etc.. I have no idea what formulas were used in determining all of the factors. It did use a few things from the Firefighter .12 kit but some changes to the width of the sponsons as it was designed to be run in the rougher waters of Japan. We did some experimenting with it here in the States for the calmer water with narrower sponsons but kept the stance width the same. It has the smaller CMD Eagle SG styled rear sponsons.

TCHedOff

Thanks for sharing the pic - Nice Boat!

Where can I get the answers I'm looking for - email some of the top boat designers (?), or is there a better forum to post the question on sponsons? I could always copy from another boat design, or try an amalgamated design based on serval sponsons of boat in the .12 -.18 size - but these approaches would be just guesstimates. I'd like to do better.

PS was thinking of sending the engine off to [email protected] to tweak. Know anyone who has tried their services? My email to them bounced back (and that makes me suspicious).

Ron Olson

My Feedback: (1)

If you want to save time, money and the hassle of building one from scratch you can get a Firefighter 12 for around $70.00 at www.firefighterboats.com or through the Climate Boatworks website.

TCHedOff

I've checked out firefighters (and others), but I want to try a couple things (hopefully innovations) - and I've made a plan of the basic hull I'm working with so I can go back and re-work things as necessary.

The reason I asked about sponson surface area is I want to build a (unique??) 3 pt rigger that runs on 3 sponsons - the two in front, and then take a 3rd sponson which is really just a slightly angled up surface like a trim tab for the final 1-1/4"of the boats bottom. I want to try to set the boat to run on these 3 surfaces. I've angled the tail surface @ 2-3 degrees.

This 1st attempt uses a flat surface, but I also want to try the same 3pt approach with a slight "v" (like a monohull) running for final 1-1/4" at the end of the boat..... and hopefully the v shape will act like a rudder keeping the rear of the boat in-line, and then I could do
away with a rudder assembly, yet still have a controllable boat.

I think these approaches have some merit, and none of the designs I've seen incorporate them... perhaps they have been tried before, and scrapped for one reason or another?

TCHedOff

I've put a pic of the body in my gallery...

I’ve been looking at a lot of sponsons for ideas on a scratch .12 sized rigger I’ve been working on. There seems to be a wide range of variances in size shape and angles. Here’s a link to a design that I found the most interesting:
http://www.rcuniverse.com/market/ite...933-0-1028.jpg

I like the design on the bottom of these alot and I’d like to hear suggestions and advice on scaling these sponsons down to a .12 class design – the dimensions for my boat’s body are 20-1/4” long and 3-7/8” wide. What lengths and widths should I be considering?