Hobie/J24 Trimaran Conversion

[ImaginaryNumber]

Doug, here you are.

[Doug Lord]

Thanks, IN-I'm amazed-just plain amazed. I agree with oldsailor:

Originally Posted by oldsailor7

I'm sorry Delaine, I am not trying to be Snide. But I really don't know where to start in commenting on the evolution of your Tri.

I have never liked the J24.
I always considered it as a fat little Mono with a heavy keel. It's performance was nothing to write home about ---but it was a successful class racer.
As a pocket cruiser it was unpleasant. It rolled horribly, it had convex decks, it had low "safety" rails which were so low they were more likely to trip you overboard rather than save you.
A couple of years ago I was offered one for free because the owner couldn't sell it.
I turned it down.

Although the hull has a typical mono low B/L ratio, stripped of it's dead weight keel it has the opportunity to plane, given enough sail power. As a Tri you had the opportunity to add a great deal more sail power.
Your conversion was sufficient to give you a pleasant sailing boat, although I worried about the holes you drilled in the cross arms and the lack of water stays.
Water stays protect the crossarms from bending stress and convert it into compressive stress which the tubular arms can handle very well.

However I can't understand why you wanted to add the add the underbody to the hull except for its ability for reduce leeway. It is a good semicircular section for low friction drag, but the straight keel line
is going to slow down your ability to turn quickly and the flat back end is going to produce a lot of vortex drag and turbulence which will affect the operation of the rudder, particularly when turning to Port.
Just my 2C worth.

[Corley]

I liked your first interpretation better with the standard J24 hull.

[warwick]

I agree Corley in using the original hull would have been a better idea. i understand there was an Americas cup 12 metre that tried a similar under water section at the back. It looked promising in testing but proved a failure when used full size. you may end up with extra drag for no gain.

May be just adding floats may have been a better idea initially.

[Delane]

Almost ready to launch and establish new waterline.

[oldsailor7]

Delane.
Your workmanship is terrific----but I for the life of me I can't see to what purpose.

[Delane]

My hopes are to increase speed through the slenderness ratio of 13:1 and reduce the form stability drag I had before. I'm still learning and figured that a Torpedo going through the water was faster than a bath tub. I may add water stays now. Thinking more on the rudder placement.

[Delane]

Built this in 5 sections and each is sealed off and full of 2 liter pressurized PET bottles.

[cavalier mk2]

The immersed transom is going to be turbulent..... Watch out for broaching with the deep bow, it is a lot to trip over if you get sideways.

[luff tension]

With all that extra buoyancy under the main hull and no changes to the floats you will notice a dramatic decrease heel angle while sailing, my guess is it will be slower and much harder to steer.
How easy are the mods going to be to chop off once you have found they dont work?

[warwick]

I think it is a good point Luff tension brings up how easy would it be to revert to the original hull form if it does not work out.

On the Americas cup boat (one as designed one converted) with a cut off under water section there was a lot of drag, and reverted back to a more normal hull form.

[Delane]

Yes I've planned to lower the Ama's all along for obvious reasons. I may launch today to see the new water line and to see if she's level or not. This will provide the new drop measurements for the new Ama mounting hardware.

And yes if this mod doesn't work out, I have a chop saw and speed grinders standing by will not hesitate to cut it all off.

I do know that she won't turn like she did and can except that and be prepared to use the motor to aid in turning in tight spots.

With that said the jury is out in deliberation and only time and testing will reveal the results.

Optimism is high, with a slight hint of worry. But I'm not suppose to say that right?

[oldsailor7]

Originally Posted by Delane

Optimism is high, with a slight hint of worry. But I'm not suppose to say that right?

LOL Delane.

[Gary Baigent]

Well, goodonyer, Delane mate, for following through a "revelation-ary"(I didn't say revolutionary) idea and actually producing something. But if you wanted a narrow main hull, imo, you would have been better off building one from scratch and not tacking it onto the bottom of a monohull. It's obvious that to do so (building afresh) would easily be in your skills and capabilities. However learning-the-hard-way is my middle name too... but you do really learn ... and I look forward to seeing your next improved project based on the hard won knowledge you're going to receive from this boat.

[Delane]

Thanks Gary, and yes sometimes the school of doing something wrong verses doing nothing at all has it's merit.

People spend good money every day listening to Professor's tell them stories (full of lies) to which they gain/draw no practical experience if not applied in some form.

Time, money and options to follow.

Stay Tuned!