Stiletto Catamaran Modifacations ?

[Cat Sailor]

As summer gets nearer I am dedicating myself to modifying my stiletto 23 catamaran. I would like to add hobie cat style bench seats or wings as they are known.
I got a set of Hobie 21 wings which are the tube and socket type. Tubes are permanently sunk through the deck, across the interior space, and bonded into the bilge area. The tubes are glassed solid where they pass throught the deck and where they meet the skin in the bilge area. The wings simply drop into the tubes.
I am wondering if I should make some sort of bulkhead or ring frame and bond the tubes to them or just beef up the interior skin of the hull with an oversized pad of roving and bond the tubes directly to this pad.
The roving pad will be far easier but I am concerned about localized stresses since the skin is a light weight composit of kevlar epoxy and nomex honeycomb. I am not sure if it is designed for the kinds of stresses that these tubes will aply. The wings are rated for 500lb which is 250lbs per tube. Any coments you have about this plan would be helpfull.

This is a link to a photo of a hobie cat with this set up

http://stiletto.wildjibe.com/portfol...3/photo_22.jpg

Thanks

Cat Sailor
Cranston RI

HI;

The H21 wing mounting is a high stress to the hull deck. There are two points of contact alog the length of the internal tube. Over 5 years of racing the 21 we "reafixed" the wing wells twice.

Stabilizing the wings with preventers fore and aft help keep the minute movemnets when wings are fully loaded (sitting). When on the wire the load is more evenly distributed.

If engineered correctly it is a GREAT setup for comfort, visability, and performance.

If you need specific advice; just email.

Mark
mark.hibbard@wccc.me.edu

Originally Posted by Cat Sailor

As summer gets nearer I am dedicating myself to modifying my stiletto 23 catamaran. I would like to add hobie cat style bench seats or wings as they are known.
I got a set of Hobie 21 wings which are the tube and socket type. Tubes are permanently sunk through the deck, across the interior space, and bonded into the bilge area. The tubes are glassed solid where they pass throught the deck and where they meet the skin in the bilge area. The wings simply drop into the tubes.
I am wondering if I should make some sort of bulkhead or ring frame and bond the tubes to them or just beef up the interior skin of the hull with an oversized pad of roving and bond the tubes directly to this pad.
The roving pad will be far easier but I am concerned about localized stresses since the skin is a light weight composit of kevlar epoxy and nomex honeycomb. I am not sure if it is designed for the kinds of stresses that these tubes will aply. The wings are rated for 500lb which is 250lbs per tube. Any coments you have about this plan would be helpfull.

This is a link to a photo of a hobie cat with this set up

http://stiletto.wildjibe.com/portfol...3/photo_22.jpg

Thanks

Cat Sailor
Cranston RI

[sorenfdk]

Originally Posted by Cat Sailor

I am wondering if I should make some sort of bulkhead or ring frame and bond the tubes to them or just beef up the interior skin of the hull with an oversized pad of roving and bond the tubes directly to this pad.
The roving pad will be far easier but I am concerned about localized stresses since the skin is a light weight composit of kevlar epoxy and nomex honeycomb. I am not sure if it is designed for the kinds of stresses that these tubes will aply. The wings are rated for 500lb which is 250lbs per tube. Any coments you have about this plan would be helpfull.

I don't know the internal structure of the Hobiecat, but as you can see from the picture, the forward tube is located just aft of the forward crossbeam. These two things together make this a highly loaded area, so I bet there's a bulkhead or a ringframe in there just between the tube and the crossbeam.

In your case, the glue area between the skin and the honeycomb core is very small, so if you attach the end of the tube to the inner skin, you'll probably experience severe core debonding sooner or later, unless you make the pad really large.

I would go for the bulkhead solution, but beef the inner skin up with a pad before you glass the bulkhead in. If the aft tube will be located close to the transom (as on the Hobiecat), then this solution may be difficult, so here you can use the pad, but the pad should go all the way to the transom and (at least) an equal distance forward of the tube.