Two boats on a Kitty Hawk -- the Laser sandwich

a-rog

New Member
I made this rig to carry two boats because it's way funner to sail with a friend or your brother or your kid. And that's what I've been up to this summer.

It's still plenty warm here in northern Illinois, so I'm not done for the season. But after building this rig and dragging it around the country, I can now report on lessons learned. I'm planning version 2.0, so I hope you'll add your ideas and suggestions.

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Lesson 1: different padding material. I used rigid foam (the gray stuff, like you'd use to carry kayaks on a car). One of my boats now has faint yellow stains where the foam contacted the deck. (The 30-year-old boat has the stains; the 20-year-old boat stayed clean.) Next time I'll try something like a vinyl covering that's sturdy and won't stain the boats.

Lesson 2: better clearance. My spars were a tad close to the deck, and left a couple of rub marks. And as the foam compressed and things wobbled and settled, the plywood and bungee cord hooks ooched closer and closer to the deck, eventually leaving a couple of gouges in the gel coat. Not terrible, but not good.

Lesson 3: four bolts ain't enough. These rigs have two plywood planks compressing two chunks of foam using two bolts on each side. This worked initially, but as the foam began to conform with the pressure, things loosened and the rig started to twist. In the next version I may use extruded polystyrene and glue for the inner bracing. Would this hold up to the elements?

Lesson 4: support only at the outer edge. I tried to cut the foam so it tapered to the outside -- greatest thickness at the outer 2-3 inches. Wanted to avoid any weight/pressure on the non-reinforced parts of the deck. But foam likes to spread out and be all mushy and distribute weight. Usually a good thing, but not in this case. Next time I'll make a box structure and add foam pads only at the edges.

For version 2.0, I'm thinking it will look like a hybrid between these two designs:
Kitty Hawk Trailers - Custom trailers to transport Laser sailboats
http://sailingforums.com/attachments/img00031-jpg.5714/

Lesson 5: the Kitty Hawk handles two boats beautifully. I interviewed people about this during planning. My mechanic said he thought the structure and springs would be fine. Others thought it looked a bit flimsy. But I can now report that my 20-year-old galvanized Kitty Hawk trailer has carried two boats to Florida, Wisconsin, and downtown Chicago -- totaling about 2,500 miles. The bounce factor is reduced with the weight of the second hull. And the bending and giving of the trailer's light structure probably helps keep those welds happy. How many years will it last? I'm interested in your opinions.

I'm really interested to know if others have tried this, and how it's worked out. I'll keep you posted on the progress of my next version.

Meantime, happy sailing.

-andy
 
BTW, for materials I'm looking at this 1/2" PVC trim for the planks and two layers of 2" extruded polystyrene for the filler. Glued together and maybe (maybe not?) bolted.

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This might give you some ideas.

The width of the "bars" is about 20cm, which distributes the load nicely. 10 spar slots. The 4 spares permit you to carry a complete spare set including if necessary a spare standard and radial bottom section. When not in use, those slots can be filled in and become load bearing. To assist in placing the spars in place, the middle can be raised. Not shown is the key holing to stop the top sliding off the bottom in the middle and the key hole to rece the pressure on the traveller cleat.
 

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Additionally, there is no need to tie the spars down, once a boat is loaded on top the EVA foam provides sufficient friction to hold the spars in place.
 

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