I posted this on a boat building forum but though I might get more relevent answers here.


Short version, are there any cat designs for sale where the hulls could be used with Hobie 18SX rigging, if so which ones?

Long, drawn out version...

My wife and I sail an older Hobie 18SX on the weekends usually between some local islands within 11nm (22km) of shore. No racing, just island hopping with other Hobie sailing if the weather permits or just blasting around off the beach if a long sail looks questionable. We enjoy this boat, with the possible exception of its weight (way over class weight), but it is starting to show its age. The hulls have been injected with epoxy once already due to delamination and I'll be doing this again soon it seems... I also have to track down some leaks as we are taking on a lot more water then is normal.

This boat has been out of production since 2003 but there are lots of spare parts available as well as used boats on the market. I have extra crossbars and dolphin striker in the garage. The last few boats I checked out also had soft hulls so didn't make the cut for spare parts boats.

In the past I have toyed with the idea of building a lighter cat such as the Blade F16 due to being at least as fast as our 18SX (probably faster), much lighter (don't need as many people to help move it on the beach), carries its buoyancy low (reduced tendency to pitch pole was one of the reasons we chose the 18 over a Hobie 16), but couldn't justify the cost of a modern racing rig just to fun sail. I've often seen it mentioned that building the hulls for a project like this is the least expensive part with the rig, sails, foils, etc. usually costing much more.

So the question is would it be feasible to build new, modern hulls (preferably out of ply/epoxy) as a winter project and use most of the parts of the old Hobie, with the possible exception of the dagger boards since the trunks are usually part of the hull design?



Specifications
Length 18'
Beam 8'
Min. Class Weight 400 lbs.
Draft (Boards Down) 2'6'
Mast Length 29'6.5'
Total Sail Area 240 sq. ft.
Maximum SX Wing Load 550 lbs.
Hull Construction Fiberglass/Foam Sandwich




(Typical boat, not mine)

Yes it would be very feasible, but you'll be creating a hard to sell orphan. I honestly believe you'd be better off selling the current boat and re-investing the proceeds into a home build.

If you want to go ahead with the new hull option contact Phill about the Blade 18.

A couple of ideas,
1. Plywood Tornado hulls are easy to build and the design is in the public domain. Possibly the only design modification you would need is to relocate the main and rear bulkhead locations and the re-shape of the bean channels.
2. Since you seem to really like the Hobie 18, why not use an existing hull as a plug for a female mold. Then you could mold a set of new H 18 hulls from advanced and much lighter/stronger materials. The conventional wisdom is not to use the female mold method for a one-off project but since you allready have a male "plug" available, a lot of the work is done.

Kevin

Doing a mould for just two hulls sounds like quite some work for a beginner at boatbuilding?

There are 18 foot plywood designs out there where you surely can re-use all the parts. Doing a set of Tornado hulls might not be a bad idea either as long as you are putting the 18SX rig on it. You can even fit the 18SX foils instead of the centerboards.

Scarecrow touches a very important point. Resale value for this one of a kind boat will not be as good as for a boat belonging to an established class. One should always bear this in mind, even if a sale is not planned. One day..
If you already are willing to invest time in building a set of plywood hulls, why not go for F16 hulls and fit your parts to those hulls. Might have to work a bit on the rig to make it fit in the F16 rules, but at least it would be part of a class.

If you are not interested in racing try to find a design that you can build out of foam/glass. Build as light as possible, it's a real plesure to have a light boat when you have to carry it around.
Tortured ply hulls are fun to build, but the outcome is never quite sure, and it's involvig a lot of filler and sanding...
And last, don't dream of second hand value on a homebuilt boat.

You might have a good point there.. The Mosquito and Taipan 4.9 classes have an amount of homebuilts and they seem sellable?

Thanks for all the input guys. I wasn't thinking resale value at all in this. I'm the type of guy who drives a car till its ready for the junk yard instead of trading it in every few years.

I had thought about the Blade F16 (I love the looks of that boat!) but in an email exchange with Phill last year he didn't think that would be the best choice for the type of sailing we do and suggested something bigger, around 20', might be a better option.

I haven't heard of the Blade F18 plans being available for homebuilders so the Tornado might be a good choice. I would probably build it with the swing boards. Although hitting a submerged rock four or five years ago and breaking 4" off a daggerboard did give me a chance to learn foam/glass/epoxy repair. <img src="http://www.catsailor.com/forums/images/graemlins/blush.gif" alt="" />

As for foam/glass vs. ply/epoxy, which is actually lighter? I thought it was the ply but have no real reason to think that other than following projects such as the Blade that seem to work well in wood.

I don't think either method has a clear advantage in terms of strength per pound or stiffness per pound. The materials that can be used in foam/glass comprise a wide variety of fibers and core materials so the answer is "it depends". At the high end, using carbon, kevlar, high performance foam and vacuum bagging, the sandwich construction is more efficient.
I have built hulls using both methods and for a home builder I think tortured ply is less hours and less chance of making any serious mistakes. Some people much prefer working with wood opposed to composites because of asthetics and comfort. Lots of opinions on this.

Kevin

Here is my Hobie 17 with an 18 mast and sails...

http://www.hobiecat.com/community/viewtopic.php?t=10673

Very Cool! I like the coolers installed in the decks. Looks like 3 crew may be a little much for the buoyancy. But it should cook w/ the TheMightyHobie18 rig. Well done!

Yes, 3 people is a bit much (it is, afterall a Hobie 17, which was designed to be a single handed racer). However, it does cook with the 18 setup. Check out the youtube video I posted with 3 of us sailing. <img src="http://www.catsailor.com/forums/images/graemlins/smile.gif" alt="" />

http://www.youtube.com/watch?v=I5hGu4ysb2o

I have yet to sail it in a good wind alone.