Converting power catamaran to sailing catamaran

[canyonbat]

Assuming you succeed, what are you left with? A boat that is going to have limited resale value and will be very hard to insure. Even worse, if you start on this project and do not finish after the the three or four years it might take (paying yard fees the entire time) you will be stuck with a giant white elephant. If you are in love with the layout, just keep it as a motor sailor. For the cost of the conversion you can buy a lot of fuel.

[Gaia]

Easy peasy Bill. Install a unstayed junk rig a la our Tom Colvin Gazelle GAIA with Sunbird rig. No ridiculous compression loads, simple to reef and do everything else in safety from the cockpit, low aspect ratio, low cost, low loads all around.

Or be really different and go like Pete Hill with his twin junk rigs on China Moon. Harder to do and harder on inside accomodation but fascinating concept.

Jim PS our Gazelle GAIA is now for sale after a 23 yr long single navigation but that will not likely appeal to you☺️

[tiopirata]

Do Denny, who has contributed here, would be my choice to engineer this.

[Suijin]

Originally Posted by ranchero76

Pricewise...Let's put price of the boat aside for now. Let's say it's free.
I'm willing to do ALL or most modification work myself. I'd use used mast of proper size.
I'm engineer, but not a naval engineer.
...
What would be your estimate - would such project make sense at all assuming it's unique boat and only other option would be to build sailing catamaran with similar layout from scratch?

This is nuts.

The only way you're going to know if this makes sense is by A) getting valid design and build specifications for the existing boat, and B) hiring a naval architect to evaluate them and design a solution or tell you it cannot be done. No one here can give you any meaningful advice whatsoever with respect to whether it's possible, much less how much it would cost.

There is a lot more to it than making sure the hull itself is strong enough. There is standing rig design and specifications, running rigging geometry and hard points. You have a lot of lines you need to control, winches, jib tracks etc.

There may be modifications to the bottom required as in adding keels, modifying rudders, etc.

IMHO this is a fool's errand for someone who does not know much about boats. Perhaps it's a good thought experiment, but modifying and rigging a boat of that size to perform well and be safe is going to cost a fortune.

Sounds like "Flyin' Hawaiian: The Sequel".

[Gaia]

I am astounded by all the negative feedback on this topic. Hardly anyone seems willing to think outside their box. We have no idea about the cost of the power catamaran involved nor do we know how much Bill is willing to spend. We even had someone suggest buying fuel instead! Perhaps Bill is addicted to sailing like I presume most of us?

There are several cats with unstayed rigs. Forestay tension problems found on unstayed rigs can be solved, like we did on GAIA with the Camberspar, a brilliant invention. Google it.

Open your mind folks and suggest ways Bill can do what he would like to do.

If I could buy a Catamaran with a junk rig I would do it instantly.

Jim

[tiopirata]

Originally Posted by Suijin

This is nuts.

The only way you're going to know if this makes sense is by A) getting valid design and build specifications for the existing boat, and B) hiring a naval architect to evaluate them and design a solution or tell you it cannot be done. No one here can give you any meaningful advice whatsoever with respect to whether it's possible, much less how much it would cost.

There is a lot more to it than making sure the hull itself is strong enough. There is standing rig design and specifications, running rigging geometry and hard points. You have a lot of lines you need to control, winches, jib tracks etc.

There may be modifications to the bottom required as in adding keels, modifying rudders, etc.

IMHO this is a fool's errand for someone who does not know much about boats. Perhaps it's a good thought experiment, but modifying and rigging a boat of that size to perform well and be safe is going to cost a fortune.

Sounds like "Flyin' Hawaiian: The Sequel".

Both Rob Denney and myself have designed or engineered large multihulls, we have also sailed these, we probably have more than 80 years seagoing between us. This is not the difficult project some of you allege, but doing it requires a bit of 21st century thinking. Most responses here can't get past the 19th century notion of shrouds, stays, triangular sails etc. I also have a rigging company, no way will any yacht of mine ever have cable rigging supporting a spar, never again.

[Cadence]

I'd agree with post 2. It is a silly question.

[rabbi]

impossible is nothing. Does it make sense, especially economically? I doubt so.

This of course requires a naval architect and out of the box thinking. Unstayed masts sound right as no centered compression loads.


To encourage you: google "Pilar rossi", the yacht of Nelson Piquet.
Born as an odd 30m motor yacht, then converted and enlarged mutliple times, she is now a huge sailing trimaran. No clue how she sail, but she looks cool. Somewhat weird but definately cool and shows character.

[Franziska]

Even when looking at this outside the box, it will very likely end in a bad compromise with low resale value.
Not saying it can not be done, but simply from hydrostatics it will be a huge feat. Let alone structure and the rest.

Do proper calculations and present us with the before and after results.

Good luck.

By the way, show us some pictures and drawings of the boat and anyone here has a better view on the options...

[captlloyd]

Originally Posted by Gaia

I am astounded by all the negative feedback on this topic. Hardly anyone seems willing to think outside their box. We have no idea about the cost of the power catamaran involved nor do we know how much Bill is willing to spend. We even had someone suggest buying fuel instead! Perhaps Bill is addicted to sailing like I presume most of us?

There are several cats with unstayed rigs. Forestay tension problems found on unstayed rigs can be solved, like we did on GAIA with the Camberspar, a brilliant invention. Google it.

Open your mind folks and suggest ways Bill can do what he would like to do.

If I could buy a Catamaran with a junk rig I would do it instantly.

Jim

X2. Some folks on this forum have deep pockets and their answer seems to be to just “ buy it” all the time. They don’t like the idea of any of this “ do it yourself stuff”.

[CatNewBee]

I would rather buy a propper sailing cat and refit the interior instead of converting a power cat to a sailboat just because of the furniture. I would rather not risk my life on such essential things like a propper mast / rig / keels / chain plates etc.

the hulls and the decks are designed by purpose and I think, it may be doable, but all the reinforcements and changes would destroy the interior design / layout too.

It is easier to throw off the furniture and refit it than change the structure and its integrity for a totaly different propulsion system.

A 50ft sailing cat deals with serios forces, it is not like a surf board.

If its for free, sell it and buy one with sails, do your re-fit, and go sailing...

[ranchero76]

Woo, I didn't expect so many responses, especially so many "not so negative" ones.

Regarding "just move the furniture!". I still would "move the furniture and walls" on it. But this catamaran does not "just have different furniture", it has whole different boat layout, so different that it would take even more work to convert any sailing catamaran to something similar.

I almost "forgot" about unstayed rig. I actually love unstayed rigs, but they are still so uncommon and often unwelcomed by sailing community that I became "more normal".

But they do exist, including big boats. Like example below - 52ft Aerorig catamaran. Nice boat, beside the fact that this is few years old unfinished catamaran, and owner-builder is asking about 10 times more money than it's worth in its current unfinished shape.

Not sure about two free standing masts...just sounds too weird, I guess.

Regarding the value. It's not worth much as power catamaran - old power boat with huge fuel consumption.

No, it's not free. And not very cheap either. I didn't name the price to avoid discussion about "what I can buy for that kind of money and go sailing tomorrow".

When finished (if successful), as sailing catamaran I don't see why its value would be any different comparing to any other home-built sailing catamaran. Yes, nowadays there's mostly "standard thinking", everyone seems to be afraid of anything custom or home-built.
So it never will be worth as Lagoon 52. But I guess I'm not "normal", it often makes me feel good to own something "non-standard".

BTW, does anyone know owner of "Pedigree cats", who had built Aerorig from link below?

2018 Pedigree Catamarans PCB52 sailboat for sale in Washington

[CatNewBee]

A project is a project... If you feel, you can cope with it, just do it. If you are not experianced enough to do all the math and simulations, try to hire someone who can do it for you and show you where the structure needs reinforcements. If it is already a DIY custom built, you never know the strength of the structure, there are just no comparisons nor data nor tests.

A production cat has at least some calculation you can rely on or you can contact the manufacturer and ask for advice.

So if it is a home built vessel, it will be more try and error...

[Cheechako]

Most power cats are narrower than sail cats right? So you'll have to limit your sail area quite a bit.

[ranchero76]

Originally Posted by Cheechako

Most power cats are narrower than sail cats right? So you'll have to limit your sail area quite a bit.

Beam is over 26 ft.