Who Makes a Large Catamaran with Outboards

[beiland]

Originally Posted by Cheechako

For smaller cats I like the dual outboard approach. Relatively inexpensive and lightweight. Easy to replace etc.

You have to be willing to go all solar or gen set I suppose though....

For lower hp requirements why not fashion something up from these small Yanmar or other diesels that the Thai people use for many of their longtail vessels.
thai boat plans needed.. - Page 3 - Boat Design Forums

You might even fashion a small diesel generator set

[Cheechako]

The longtail degin is interesting. They are actually made for use on powerboats, saw them at at commercial boat exposition. Expensive.....

[Sugarsail1]

Schionning Catamarans are designed to be fitted with outboards.

[sailjumanji]

Maybe you don't consider this "large", but Seawind has produced a 1000 (33 ft) and 1000XL (36 ft) for many years - including current. Probably one of their most successful. Powered by twin 9.9 hp Yamaha hi-thrust or 15 hp. Pushes the boat at hull speed of 7-8 knots at WOT. Of course, they are really meant to sail.

I had about 2000 hrs on my original Yamaha 9.9's, when one of them cratered. Repower was easy as they sit in a box. They are not prone to theft. There is a mechanical system that raises and lowers the motor. I much prefer the outboards, are easy to service, and easy to replace when the time comes.

Its also a very nice sailing boat, with wide main traveler in the back, sprit for screacher and/or spinnaker, self-tailing jib, dual wheels. I moved to this after racing Corsair 24's and Corsair 28R's for years. It is obviously not as fast, but much more comfortable.

[daysgoneby]

I'll add this one because it's cool Aspen Power Catamarans | 28', 32', 38', 48' Cruising Catamaran

Argus Boats - E35 Cruising Power Catamaran

ArrowCat Marine | 30, 32 and 42 foot Offshore Power and Fishing Catamarans

2007 Buzzards Bay 34' 2' (10.41m) - Northstar Yacht Sales

37' Powercat - Kernan Yacht Design

[JimmyDarci]

We have a Crowther 46 sailing cat with twin Yamaha T9.9 (high thrust/low gear ratio/special props). Works great 85% of the time.... She pivots on a dime with tiny outboards in low wind situations and gets up to 6 knots for hours on end no problem under power.

That said, the other 15% of the time is a work in progress: headwinds at low speed and turning with no speed into a heavy wind is a bitch due to windage. Creativity usually provides a solution (heading downwind to gain speed or using an extra line to pivot off the mooring) ... but ... we are absolutely upgrading to Yamaha T25Xwtc engines. Extra long shafts (25" for low cavitation) and high thrust prop/gearing version, and also looking at installing jackplates with a 6.8 inch vertical drop electro/hydrolic quick raise (made by several companies including seastar and Atlas / H-C Marine).

Either way, we currently get up to an extra 2 knots sailing when we raise the 9.9 engines and not a big deal to lift them. Super easy maintenance on OBs and only $3k a pop for the 9.9 high thrust versus much more for diesel. Also, Yamaha 25s are EFI (no carb) and very fuel efficient.

Regarding theft, the 25hp engine weighs 154.8 lbs and will be through bolted in three places with locking lug nuts. Not too worried about theft with bigger OBs. The 9.9s are only 98 lbs and more vulnerable. I would further note that cats usually are at anchor or a mooring when travelling (at least we are) and it would be more difficult to float up and muscle off engines compared to when at the dock. (Yes, I am sure somebody has had this happen but just saying, more difficult to remove an outboard while balancing in a dinghy.)

I have owned my fair share of diesels on prior boats. I really like the obs for the following reasons - weight, interior space, cost, easy maintenance. Throw in the EFI and the fuel and reliability go up even further. Today's outboards are not the same as those our fathers owned.

[sailjumanji]

Wow, youve resurrected an old topic. Last time i posted on it we had a Seawind 1000 (33 ft) cat with twin 9.9 hp outboards. Now have a 2019 Seawind 1160 (38 ft) Lite with twin 25 hp Yamaha high-thrust outboards. Have 800 watts solar, propane stove and bbq. Solar covers it all except air condition. For that 18k btu unit, we power with a Honda 2200 generator. We have over 2300 nm on the boat, and around 200 hrs on the engines. Sails very well, which is what we prefer over motoring. But the motors are quite adequate for propulsion too. And when sailing we are not dragging props!

[JimmyDarci]

Sounds like a fantastic setup and appreciate hearing from you on this. We are buying Yamaha T25 engines for refit and searching hard for extra long shafts - 25”. Seemingly the 25” not available anywhere on East coast right now. Considering jackplates to raise and lower regular Yamaha T25lwtc engines instead. Will use solar system onboard to power the jackplates. Do you like the YamahaT25 engines? Are they sufficient for you? We love being able to raise the engines out of the water and go a couple knots faster with them out. Pretty cool reason to use outboards. Just hoping the T25 is sufficient and lives up to its billing. Current T9.9s on the 46 just not enough.

[sailjumanji]

Originally Posted by JimmyDarci

Sounds like a fantastic setup and appreciate hearing from you on this. We are buying Yamaha T25 engines for refit and searching hard for extra long shafts - 25”. Seemingly the 25” not available anywhere on East coast right now. Considering jackplates to raise and lower regular Yamaha T25lwtc engines instead. Will use solar system onboard to power the jackplates. Do you like the YamahaT25 engines? Are they sufficient for you? We love being able to raise the engines out of the water and go a couple knots faster with them out. Pretty cool reason to use outboards. Just hoping the T25 is sufficient and lives up to its billing. Current T9.9s on the 46 just not enough.

Sorry, until now I missed your questions. I like the Yamaha outboards. We actually have the extra long shaft T25XA's. These are 2018 motors, that as far as I have determined are not available in the US. (None of the online parts diagrams are for XA's, and the dealer doesn't recognize existence either.) But the Seawind was made in Vietnam, and there are apparently available there.

Our boat is around 38 ft LWL and 7 tons. She sails very nice. I have found the 25's to be enough motor for maneuvering around docks, and even motoring long distances. At about 3200 RPMs we burn 1.6 gal per hour with both engines running, and speed about 6-6.5 knots loaded for cruising. When we push it - for instance like a few days ago to pass a barge in teh ICW - we can get up to hull speed around 8.2 knots. When the boat was new and empty, and the bottom really perfect, we made 8 knots at about 3500 RPM's. (We motored from Miami to Stuart, FL with the mast in halves on the deck, on the way to commission the boat.)

We've not had any problems with the 25's. I had to clean the carb on one of them. That said, we only have about 220 hours on the motors. Our motors have permanent nacelles to protect them. We just use the stock tilt/trim mechanism to raise clear from the water.

[Enza]

Does anyone have any thoughts on the Yanmar 50 HP outboard diesels set up in the same configuration as the Seawind lite? I'm wondering about this with modifying a Lagoon 440.

[Sparx]

The sailing catamarans with outboard auxiliaries, including Seawinds, mount the outboards well forward of the transoms to keep the engines submerged when in a chop. Typically the engines are in the vicinity of 65 to 80 percent of the waterline length from the bow. This requires building special mounting systems between the hulls. Retrofitting into a Lagoon 440 would be a huge mod. I would not do this.

[JimmyDarci]

Originally Posted by Sparx

The sailing catamarans with outboard auxiliaries, including Seawinds, mount the outboards well forward of the transoms to keep the engines submerged when in a chop. Typically the engines are in the vicinity of 65 to 80 percent of the waterline length from the bow. This requires building special mounting systems between the hulls. Retrofitting into a Lagoon 440 would be a huge mod. I would not do this.

Your post about Seawind 1160 lite type cats sparked my curiosity, since our cat uses extra long shaft outboards a bit farther back to avoid the cavitation issues. Our Yamaha 25” shaft obs rely upon the extra length to avoid cavitation during larger wave chop. Seawind style design is awesome but not likely for a retrofit.

Seawind tech specs show that it uses Honda 20hp. I could not get the Honda in a 25” when I looked last year so I am assuming it uses standard 20” shafts positioned farther forward as described above. For the poster’s retrofit project, perhaps the extra long Yamaha 25” shafts would provide an option? Yamaha also makes very good high thrust extra long outboards that provide a fuel efficient and strong propulsion system for the horse power. All in the gearing and prop but it makes a difference. Little 9.9hp XWTC engines pushed our cat up to 6.5 knots on in fair conditions. They also make same extra long shafts in a 25hp with high thrust.