Catamaran with a Tabernacle / Mastendr / Gin Pole ?

[Dave-in-RI]

Has anyone ever come across a production catamaran with a tabernacle mast that's not a zillion dollars? I've been searching around and haven't found much luck, thought I'd ask here. Someday when I want to move up from my Sun Cat, I'll be going to a catamaran design and would love one with a hinged mast designed for on-water raising and lowering. There are plenty of trailerable catamarans and trimarans, but many of these take an hour of stepping or unstepping, designed for relocating the boat not for going under low bridges on the regular. I like the older Prout designs from the UK but am not having much luck finding something even halfway as simple as the Mastendr Plus. The Brits and Dutch have some amazing tabernacle designs for their canals but no one seems to have put one onto a sailing cat. Maybe someday I'll get a fish on this bobber of a post...

[bruce]

Interesting question, Dave. Sounds like a fun custom project! A couple of thoughts.

It could be done if there was a demand, but if I'm looking for a trailerable boat I'm leaning towards monohulls. Folding up a multihull to be road legal is a bigger engineering challenge, and is going to mean a significant set up time. I'm not sure a Mastendr system is going to make much a difference there. Similarly, if I'm doing canals and locks in Europe, beam is also limiting in most cases.

Catboats lend themselves to the Mastendr system because the mast is stepped so far forward, and they are usually gaff rigged, carrying a shorter mast than an equivalent Bermudian rig. On the trailer the mast doesn't extend much beyond the transom. Bermudian rigs typically step the mast on the trailer and slide it forward, even if the standing rigging stays in place. The whole Com-Pac line seems to maximize their trailerablity. You could put a gaff rig on a cat, haven't seen that either.

I haven't sailed on more than couple catamarans, but what I have read is that their design stiffness to heeling makes sailing to numbers more important. With a monohull, if you get overpowered and heel, wind is spilled to help mitigate the problem. On multihull, the rig can be overly stressed in similar conditions because the boat doesn't heel readily and, unfortunately, capsizes can happen. Having to engineer a tabernacle that could withstand the increased stresses that might be seen on a multihull would be marketing factor.

[Dave-in-RI]

Thanks, Bruce. I read a few books my father had collected when researching ocean crossing cats (before he had a stroke that put him in dry dock at home), and they're essentially capsize proof when you get into the sail area and forces with beam. They get a bad rap due to Hobie type beach cats, but on a typical 42' cruising cat, the sail has a heeling force equal to a regular size windsurfer sail. You'd have to have lines wrapped around lines, improperly cleated, and steering wrong during crazy winds all at once. I was very humbled by what I read, thinking they were just giant Hobie Cats with huge sails. But they are unsinkable buoyancy wise, can draw 3' of water, can have multiple adult size cabins, have so much living and cockpit space, can cruise all day level (no heeling), and easily zip around at 10-15mph no problem. And a 10hp outboard in a well will push it nearly half that on pennies of fuel. Soooo I wouldn't be looking for a trailerable anymore, that'd be a coastal cruiser. I'd just want to be able to do some bridges up in the NY canal system, some Maine ports, and hey maybe even my home port here in RI depending on beam. The cats that do the canals up north just step the mast and motor the whole way, restepping in the St Lawrence or Great Lakes. I'd prefer a power cat but need to win the power BALL.

[bruce]

I think the project is doable, to some extent anyway, but was more speaking to why there aren't examples in production to choose from.

You mentioned trailerable. Countries where inland waterways with fixed, low bridges are common have developed a tradition of masts with tabernacles, for good reason. But these waterways are often associated with canals and locks as well, reducing the market for beamy multihulls.

I agree you're not apt to capsize a 42' cruising cat, but I stand by my statement that they need to be sailed with more regard to wind loading in stronger conditions than a monohull. At 10-15 kts nobody has a problem.

Engineering a tabernacled mast that will be as strong as an untabernacled mast shouldn't be hard, but at 42' the standing rigging isn't going to be as simple as the headstay and shrouds on your gaff-rigged SC. That mast will require a lot of support, complicated and heavy rigging, and the mast itself will be heavy and require serious rigging to lower and raise, or a large counter weight below the tabernacle (double the weight, high in the boat). The mast will be 60-70', so about half will extend beyond the stern, unsupported. And, what about a headsail?

Scaling down the size of the boat will help of course, maybe with a gaff rig. At this point I would look at the size of boat you really need, what available boats would be suitable, and other possible rigging options that have developed in regions that have a tradition of routinely dropping the mast for low bridges.

Then, of course, you'll have to revisit how suitable this boat would be for general coastal passages. Fun project. Sounds expensive unless you could find a demasted boat that fit your needs. One that hit a bridge, or failed to reef soon enough in heavy weather!

[Dave-in-RI]

You've got me thinking with the dismasted boat. Wonder how fast I could make one with small fuel efficient outboards / what sizes would fit in the well (or twins on each hull to turn like a tank) ; then I don't need to worry about masts and bridges at all. It's not the sailing I'm after but the greater distance at low cost, livable space, unsinkability, shallow draft, and smooth ride in chop. Though I'm going to look a bit more for the tabernacle unicorn before fully committing to a train of thought. Thanks.

[Dave-in-RI]

By the way, you ever see an Aerorig? Seen a few big sailing cats with them and watched some videos; pretty neat.

[bruce]

Hadn't seen the Aerorig. Freestanding rotating mast, but sorry, I don't see a tabernacle in its future. The bearing must be a bear! Reminds me of a proa.

For oddly-rigged cats, we did have a Chris White Atlantic MastFoil 47 at a local marina. Two foiled masts, each with a boomed jib. The mast doesn't rotate, just the foil. Sails under the foils alone in stronger conditions. Does have a basic standing rigging, each mast has a headstay and two shrouds, but no spreaders, diamonds, lower shrouds or running backstays. No tabernacle potential here either.
https://www.chriswhitedesigns.com/atlantic-47-mastfoil
https://chriswhitedesigns.smugmug.com/Other/Prototype/i-vHwHGJ4

[Jim in TC]

We had one of those MastFoils, or something very much like it, in the marina for a couple weeks in September, without knowing quite what we were looking at...

[bruce]

Here's a couple more of the 47 underway.
https://www.youtube.com/watch?v=E6wMxvI5Qd4&list=PLlnaOLAIb4meNTvrq1z-PiWSUJ0l17heU&t=2s
https://www.youtube.com/watch?v=gTzBLvqxKdE&list=PLlnaOLAIb4meNTvrq1z-PiWSUJ0l17heU&index=3

The prototype did pretty well under foil alone in 14 kts.