Hobie Cat Lateen Conversion

Hello, all!

I couple of years ago I had a thread on here asking about converting my Hobie 16 from its default sailplan over to another rig type in an attempt to make the boat a little more docile and fit my personality better. After seeing all the responses in that thread, doing some additional research and considering my different options, I have decided to move forward with the process of completely converting the boat over to a split-masted, Flying Lateen™ rig. In this thread, I am going to share with all of you the process that I am going through and keep you apprised of the developments.

I have already begun some of the conversion, so I will first bring you up to speed.

The project began when the 40-year-old trampoline disintegrated on the way to the DMV to register the trailer. I removed the old trampoline, and then decided that, since I was going to be putting on a new trampoline anyway, I should change the way it attaches to the boat so that it would fit my vision of the new boat better.

The quote from MultihullNets.com came in at about $400, but thanks to some birthday-card money, it turned out that a heavy-duty sewing machine and 2.5 yards of marine-grade vinyl would cost only about $150 out-of-pocket, so I decided to go that route.

Following is an image of the design I developed for the sling to hold the new tramp in place. This, to me, is the real triumph of this part of the project.

The first step was to loop a rope of stainless steel cable around the four pillars. Then, I used S-hooks to connect a small piece of chain to the cable on either side of the pillar in each corner. Then, a rope was drawn in from each chain to a welded steel ring in the center. This allowed me create a good amount of tension on the cable without using a turnbuckle (because every turnbuckle you can buy says "Do not use to support human weight").

After that, it was just a matter of lacing the custom-made trampoline to the cable. (I have pieces of UV resistant PVC pipe on the cable to reduce chafing.)

In the pictures you can also see the new bench seats, one of which is already built and just needs to be finished and the other of which still needs its surface slats.

You can also see the last vestige of the original trampoline, which I have decided to keep there as a memento. (That, plus the fact that it could not be easily removed without taking the whole boat apart, which I totally did not feel like doing again.)

For the benches, I added a 1x4 rail that mounts onto the pillars using longer versions of the original bolts. At the ends, I used biscuit joiners to add a bit of height to the 1x4 so that the new rail would come up flush with the original metal rail. The slats then span from the wooden rail to the metal rail, resting on top of it. A little bit of reinforcement and stabilizing underneath - a quarter-round to reinforce the joint between the slats and the wooden rail, and a small standoff between the wood and steel rails - and I'll have a nice place to sit on either side of the boat, with the ability to face inboard. To me, this design is much more simple and elegant than adding wing seats.

For the new sail rig, I am going to create an arch of the UV-proof PVC, probably 1-1/2" diameter, foam infused. This will create the split mast of the Flying Lateen™ rig. A true "Flying Lateen" has a boom which then pivots along the same vertical axis as the yard, but my adapted version of it will have no boom. It'll only have the yard, more like a traditional lateen sail.

Also, unlike the real "Flying Lateen," my rig will be stayed, using the boat's original stays. There will not be a tripod effect like in the true Flying Lateen™.

More pictures and updates to follow!

CardboardKing

 

Not to rain on your parade, but you might want to rethink having your trampoline that low, especially if it’s solid material.

One of the weaknesses of Classic Hobie Cats is that they have little freeboard until they are powered up. They are a wet boat, and if one didn’t know it was normal for them to sit so low in the water, they might assume they were sinking!

The original trampoline performed pretty well in part because the front was higher following the curve of the front crossbeam. Just like the bow of a boat, this helped protect and direct water from washing over.

The other issue is the trampolines on beach cats are an important part of the structure and help to hold everything together and reduce flexing. Too much flex can easily crack the interconnect castings and loosen rivets.

If anything, since you are depowering the boat and will likely not be flying hulls, you might consider raising the whole frame by extending the “pillars”. This would get your trampoline up to a better height (still need drains) and bring your bench seating up to a wings seat height.

I still worry about the structure though as you are using the “pillars” and not the frame extrusions to draw everything together.

Just some food for thought.

Take a look at the AquaCat Lateen rig if you haven’t already for some inspiration.

Also SloCanvas and SaltCity Sailing have some of the best pricing on replacement trampolines.

 

Your thoughts about the trampoline being too low had occurred to me, too. Fortunately, that trampoline only cost me $50 and a couple afternoons worth of work to produce, so it won't be a huge tragedy if it turns out not to be the right solution.

I consider all of this to be basically in the category of "experimental prototype." After I've had it in the water a few times with the new design, I'll figure out what works and what doesn't work, and make whatever changes are appropriate based on that.

Based on my observations of the boat, however, it would seem that the original trampoline's biggest structural role would be to haul the fore and aft rails of the superstructure towards each other (because the fore and aft rails are riveted to the corner pieces, but the side rails just float inside the corners), but when I acquired the boat there was no evidence at all of there ever having been any lacing between the major portion of the trampoline and the grommet strip on the aft rail. This I see as evidence of the fact that the boat can be used without that trampoline connection between the fore and aft rails. After all, the pillars are embedded in the hull, and that seems to me a strong enough connection to stop the fore or aft rails from sliding far enough out to allow the side rails to slip out. And, if not, my cable loop should provide the necessary force to support that connection.

There is actually quite a lot of tension on that cable. I was pleasantly surprised. The whole structure seems very strong. Again, I won't know for sure how it all works together until I test it, but I am very optimistic.

 

Do you plan to add a forward beam?

 

I've thought about that, but then I keep coming back to "Why?" By splitting the mast, I'm already halving the amount of force that each one will have to carry, and I intend to continue using the boat's original side stays. So, with the original forestay and the two side stays, and a fairly robust step for each of the two new masts, I think it should function the way I intend it without having to add any extra hardware at the bow.

I checked out the Aqua Cat, and I am not attempting to duplicate that exactly. I don't like the way that it essentially incorporates the yard into the...what would you call it? Mast/forestay hybrid = "Mastay" ?

I intend for mine to function as an actual lateen sail would, just nested in between two masts instead of hoisted from a single one. I imagine, at least at first, the front/bottom end of the yard will be connected to the base of the forestay. That seems fairly traditional. But why that forward stay would need to be a solid pole instead of a wire is something I have yet to conceptualize.

 

King, I usually don't try to dis anyone building a boat, but I don't think you have a clue of what you are doing. I was a Hobie dealer and I have seen some pretty odd conversions using hobie hulls, some of them worked ok. The usual mistake as has been pointed out is over estimating the load carrying capacity of a hobie 14 or 16 set of hulls. The shape of the hulls as a pair also don't work very well unless the boat is flying one hull, so they are not very good for low speeds. A lateen rig worked pretty well on the Aqua Cats, their hull shape worked well with it but the lateen rig is not very weatherly and neither is a hobie 14 or 16. The hobies depend on speed and when you make them more "docile" you reduce them to a pontoon barge. There are some older cat designs that might work ok for your use, but a hobie is a really poor choice to start from. I also expect your butt will be dragging in the water with your low slung tramp.
A hobie tramp was made in three parts- two sides that slid into the tube groves on the front and sides, and a rear strip that went in the rear track that was just a lacing strip with grommets. the side pieces laced together down the middle and to the rear strip. They are QUITE important to the boat stiffness and structure.
IMO, what you have tried to create is not safe!
Start over with something more appropriate and save your energy and cash. Old cats are quite available and usually cheap. Try something like a Star cat, you will like the difference, with or without a lateen rig. Even an old Hobie 18 would work better, but they are usually not so inexpensive.
B

 

CBKing,
Good advice here.
Keep tinkering but go lighter, not heavier.

(Reminds me of the overloaded Hobie paddling out of Victoria Harbour in one of the Races to Alaska (R2AK.com).
Thing was so overloaded.
They didn't finish.)

 

The beauty of the AquaCat rig is that the upper sprit doubles as the forestay to create a tripod. Detaching the foot of the sprits allows the A frame mast to pivot forward and back to collapse the rig for trailering. This design also makes stepping the mast a breeze.

I’m not sure what you mean when you say splitting the mast.

The thing that is going to slow you down the most and make the boat dangerous is going to be the added weight of water on top of your solid trampoline. As BruceB stated and I mentioned earlier, these boat barely float when at rest and rely on the sail rig to be powered up to lift the hulls out of the water. At slow speeds they are very submarine-like, especially with a few people onboard. And water washing over the top is one of the quickest ways to stuff a Beachcat. That’s why most people prefer mesh to a solid material for trampolines.

I know from experience that a submerged set of Classic Hobie hulls can probably be pushed about 5MpH through the water before weight distribution becomes a big factor. Look at how low my H14 sits in the water in relation to the trampoline. A lot of effort was put into re-balancing this boat after removing parts like the sail rig and rudders then installing a battery, electric motor, and cooler so that it was safe to cruise around at slow speeds with two people onboard.

Again, I would seriously consider going back to a stock style mesh trampoline and then raising your seating if you are trying to create a cockpit like feel

Sail rigs are fun to experiment with, so I say go for trying whatever you have in mind and learn from what you try. But you need to start with a basic boat that can float safely with enough freeboard to move through the water in order for any rig to be effective.

 

I like your yacht That looks like a good conversion!
I was also an Aqua cat dealer, and I have a lot of respect for their simplicity. The 14 will give a single sail H-14 a good race in most conditions and is really easy to rig and sail. Of course, the H-14 is at its best sailing off a beach with plenty of wind and a light crew. Each good in the right conditions.
I don't think the Aqua cat style rig will scale up very well, but at its size, it is very effective.
B

 

Thanks. That was a fun build. Some of the design elements from that one, like the Ipe center console stringer which splits the trampoline in half and the HDPE plastic folding table seat backs, made their way into my current conversion SolGato.

Based on a rotomolded Getaway, SolGato features dual 1.5kW brushless motors, 600W of solar, and a LiFePo4 battery bank.

I’ve also designed a Crab Claw flying Lateen rig for it as well.




Interesting to hear about the AquaCat performance from someone like yourself. I never would have guessed they could compete with a H14. I’ve always liked the rig. Thanks for sharing.

BTW, just back from sailing my hot rodded Hobie Wave. I love the newer plastic boats not only because they can float a lot of weight, but they are also a ton of fun to launch off swell. The large volume hulls really pop off the water and cushion you like a bouncy ball when you land.

 

I like that one, it looks big enough to have some fun with, and still easy to handle . Nice boat!
Lets hear it for larger volume hulls.
Bruce

 

I'm not sure where all this weight that everyone seems to think I'm adding is supposed to be coming from. By my estimate, I've added the weight equivalent of three 1x4 planks of wood, but then I am also removing a 26 ft. aluminum mast and replacing it with two 10 ft. pieces of PVC conduit filled with polyurethane foam. I can't imagine that weighing more than the aluminum mast. I am also going down from two sails to one, and replacing the rather complex rigging with something much simpler that requires less hardware. There will be a yard instead of a boom, but again, it can't be that much heavier than the boom would have been, if at all.

I get that the boat sits low when not powered, and I totally understand the issue of the water on the trampoline. After I've had it the water, I'll be able to see where exactly the water is going to want to pool on the trampoline, and then I can add the necessary drainage. I've also though about lacing the center of the forward edge of the trampoline to the original rail, just to pull it up a bit, get it further from the water and give it a bit of a peak to encourage drainage, much how like the original trampoline was designed.

The other bench seat is now in place, and the tow vehicle just got repaired, so I plan to toss my canoe paddles on the trailer and head to the water soon, so I can at least see how it's going to perform flotation-wise.