Hobie/J24 Trimaran Conversion

[bill broome]

why? got an excess j24? sell it, buy/build a tri. this kind of plan converts money and effort into a garden ornament.

[surf boat man]

these are the pictures of the surf boat when I bought it

[Delane]

“Vitamin Sea” is near completion and should launch around the first week in June. Ordered and received a foil section, NACA 66-0012; 50cm root X 25cm tip X 71cm length) dagger board. Also utilizing H-20 daggers for the Amas and have a question regarding placement of the foil section relative to the original position of the as built J-24. Decided to use a standard J-24 Main, 110% Roller Furler and utilize water stays in addition to the existing new rigging.

Once the position of the foil section is decided, I plan to butt weld a 25mm steel rod to the flat 4mm steel plate. Next fiberglass the foil section and glue to the rod (gussets included) and then epoxy and glass up all to the bottom of the keel stub. The thought is to make it relatively strong and yet not make holes in the stub as with the original lead keel. The attached pics illustrate the foil section and plate minus the 25mm rod. The rod will protrude into the foil section 15 inches. Question is where I should place the section relative to previous. I’m thinking as far forward as possible but it looks right positioned a little further aft.

[BWD]

The foam in the picture looks light and non-structural (but very nicely shaped).
But even if it's strong foam, it's only foam, and putting metal rod in it seems a waste. The problem is there is nothing strong connecting the 2 skins.
Unless that foam is really really strong!

Under sailing or grounding load the fin could flex and the rod could tear the foam apart, unless the glass skins are very thick and strong, in which case the rod is not needed at all.
What I might put in there is a solid wood spar replacing all the foam at max chord, helping with grounding loads as well as serving as a sheer web.

But if you ground hard, I think you could really trash this kind of fin anyway, unless the skin thickness was truly enormous. Even without the lead, it's no dinghy.
The normal "light" alternative to a lead fin is a hollow steel one.
I would have considered using a daggerboard that could crush or kick up. Feel like building a trunk?

[Delane]

Yes it's true!

Had two good runs in a bit of a breeze and a great celebration barbeque with family and freinds at the Marina.

Speed to wind about 8 knots on the first run with the throttle at about 70%, sorry in the habit of translating for my power boater buddies who demand I break it down in those terms. Off wind seemed to be about the same but didn't have a JPS to verify the first day.

Well, I'll let the pictures speak a little.

Enjoy!

[Delane]

Here are some other shots of the first day!

[Zilver]

Congratulations on the completion of your project ! Nice idea and boat.

It looks like you were having a lot of fun on the maiden trip.
Please report some more observations about how she sails when you can.

Cheers, Hans

[mihari]

Congratulations!!!!!
Now we want to hear about how Sea Vitamin sails...
She looks like a fun boat...

[sharpii2]

Congrats.

I bet it even planes quicker than it did with a keel.

It might be interesting sport to race it against keel versions to see how the performance compares.

[aussiebushman]

Hi All

I'm new to this forum but not to boatbuilding or to the idea of building a tri from donor parts. Unfortunately, I have to sell the Simpson catamaran I built(see www.mainproject.info for details) and now want to build a trailerable trimaran. The idea of using a surfboat is really interesting and stops me having to find a suitable trailer sailer to convert. The advice about using Hobie 18 amas instead of the 16's I was considering is very sound.

I'm located near Sydney so if anyone knows where to locate a suitable surfboat or Hobie 18 at reasonable prices, please let me know.

Regards to all

Alan

[GOTTABSOMEWHERE]

Hey AUSSIEBUAHMAN



See my pics with 18' HOBIE and DORY lashed inside with "A" mast