Trimaran - Especially Searunner - Owners

[Pegasos]

If anyone is keen on sailing a SeaRunner 37 from Australia to Indonesia I’ve just placed an advert in the crew wanted section of CF.

[magentawave]

Does anyone have any thoughts on the best way to power a 34' Searunner (besides sailing)? Jim Brown cruised his 31' Scrimshaw with a little OB but that's a much smaller/lighter boat and later he retrofitted a sled.

[blewett_john]

Originally Posted by magentawave

Does anyone have any thoughts on the best way to power a 34' Searunner (besides sailing)? Jim Brown cruised his 31' Scrimshaw with a little OB but that's a much smaller/lighter boat and later he retrofitted a sled.

The diesel on my Searunner 37 died so I installed two 15 hp outboard motors. Go to https://buildingmytrimaran.shutterfly.com/ to see pictures of the installation.

[magentawave]

Originally Posted by blewett_john

The diesel on my Searunner 37 died so I installed two 15 hp outboard motors. Go to https://buildingmytrimaran.shutterfly.com/ to see pictures of the installation.

Do you have a link to the specific page that shows the twin OB's? I looked all over and couldn't find it.

Thanks

[Randy]

Originally Posted by magentawave

Does anyone have any thoughts on the best way to power a 34' Searunner (besides sailing)? Jim Brown cruised his 31' Scrimshaw with a little OB but that's a much smaller/lighter boat and later he retrofitted a sled.

I would power it right with a 2 cyl Beta and a feathering 3 blade prop. People sometimes use outboards but there are too many tradeoffs in reliability and real world usefulness.

[longjonsilver]

Originally Posted by Randy

I would power it right with a 2 cyl Beta and a feathering 3 blade prop. People sometimes use outboards but there are too many tradeoffs in reliability and real world usefulness.

Use a 2 cyl beta engine but consider the flex-o-fold prop.

jon

[Buzzman]

Outboards have several advantages: their fitment removes two of the most likely sources of flooding, sinking inrush - the shaft exit and the seacocks for the cooling water.
They are also loads cheaper to purchase and install - no specialist mechanical knowledge or equipment required.
You can fit two smaller motors and thus have contra-thrusting manouvrability that is not possible with a fixed shaft prop.
Or you can fit a single higher thrust motor linked to the tiller and thus have *similar* manouvrability.
Given the cumbersomeness of large, wide-beamed, wind-affected and hard to manouvre trimarans, twin outboards linked to the steering would tend to make more sense than any other, except perhaps on cost, in which case a single outboard is the lowest-cost solution.
Of course, all the above assume fitment to the wings or main hull sides, not to the transom of the main hull, which has issues for hobby-horsing and cavitation that, say, a surface-following sled does not. YMMV

[longjonsilver]

Originally Posted by Buzzman

Outboards have several advantages: their fitment removes two of the most likely sources of flooding, sinking inrush - the shaft exit and the seacocks for the cooling water.
They are also loads cheaper to purchase and install - no specialist mechanical knowledge or equipment required.
You can fit two smaller motors and thus have contra-thrusting manouvrability that is not possible with a fixed shaft prop.
Or you can fit a single higher thrust motor linked to the tiller and thus have *similar* manouvrability.
Given the cumbersomeness of large, wide-beamed, wind-affected and hard to manouvre trimarans, twin outboards linked to the steering would tend to make more sense than any other, except perhaps on cost, in which case a single outboard is the lowest-cost solution.
Of course, all the above assume fitment to the wings or main hull sides, not to the transom of the main hull, which has issues for hobby-horsing and cavitation that, say, a surface-following sled does not. YMMV

True, and well said. i guess it is just a matter of personal preference.

[clemon]

Originally Posted by magentawave

Does anyone have any thoughts on the best way to power a 34' Searunner (besides sailing)? Jim Brown cruised his 31' Scrimshaw with a little OB but that's a much smaller/lighter boat and later he retrofitted a sled.

I had a Searunner 34 with the engine mounted in the center just below the companionway stairs. I put a Beta 20 motor in with good results. The only downside was the length of the motor was tricky to accommodate, and you can't easily get at the front of the engine, which is where the water pump access is. A Beta 16 might work better, if you don't mind the lower horsepower. The Beta's are based on Kubota motors, and I had no problems with the motor.

[blewett_john]

Originally Posted by magentawave

Do you have a link to the specific page that shows the twin OB's? I looked all over and couldn't find it.

Thanks

https://buildingmytrimaran.shutterfl...ures/1280#1267
https://buildingmytrimaran.shutterfl...ures/1280#1256
https://buildingmytrimaran.shutterfl...ures/1280#1253
https://buildingmytrimaran.shutterfl...ures/1280#1250
https://buildingmytrimaran.shutterfl...ures/1280#1247
https://buildingmytrimaran.shutterfl...ures/1234#1230
https://buildingmytrimaran.shutterfl...ures/1234#1222

[magentawave]

Originally Posted by Randy

I would power it right with a 2 cyl Beta and a feathering 3 blade prop. People sometimes use outboards but there are too many tradeoffs in reliability and real world usefulness.

I PMed Mark Johnson (he built and cruises his Searunner 34) a couple times and he recommended the 3 cylinder 20 HP Yanma. He said it would cost about $10,000.00 IF I did everything myself. Aaargh. Why do you recommend a 2 cylinder Beta verses something like the 20 HP Yanmar?

Originally Posted by blewett_john

https://buildingmytrimaran.shutterfl...ures/1280#1267
https://buildingmytrimaran.shutterfl...ures/1280#1256
https://buildingmytrimaran.shutterfl...ures/1280#1253
https://buildingmytrimaran.shutterfl...ures/1280#1250
https://buildingmytrimaran.shutterfl...ures/1280#1247
https://buildingmytrimaran.shutterfl...ures/1234#1230
https://buildingmytrimaran.shutterfl...ures/1234#1222

Thanks for the links. Are the OB's all the way down in those photos? If so, it looks like the props are barely below the waterline. I guess your thinking was that the OB's would be good for smooth and glassy conditions with no waves only, like in a calm harbor, right? Are those long shafts? What HP?

Originally Posted by Buzzman

Outboards have several advantages: their fitment removes two of the most likely sources of flooding, sinking inrush - the shaft exit and the seacocks for the cooling water.
They are also loads cheaper to purchase and install - no specialist mechanical knowledge or equipment required.
You can fit two smaller motors and thus have contra-thrusting manouvrability that is not possible with a fixed shaft prop.
Or you can fit a single higher thrust motor linked to the tiller and thus have *similar* manouvrability.
Given the cumbersomeness of large, wide-beamed, wind-affected and hard to manouvre trimarans, twin outboards linked to the steering would tend to make more sense than any other, except perhaps on cost, in which case a single outboard is the lowest-cost solution.
Of course, all the above assume fitment to the wings or main hull sides, not to the transom of the main hull, which has issues for hobby-horsing and cavitation that, say, a surface-following sled does not. YMMV

Downside to OB's is that over time fuel costs will be a lot higher than a diesel, but I sure like the simplicity of OB's and having less thru hulls! The only way I could see an OB working properly on a Searunner 34 in rough conditions would be to bring it as close to amidships as possible and get the props down really low. Jim Brown accomplished that when he retrofitted a sled on his 31. The 34 though is so much bigger and heavier than the 31 and has a lot more windage. Anyone heard of an OB sled on a Searunner 34?

[Randy]

Originally Posted by longjonsilver

True, and well said. i guess it is just a matter of personal preference. [emoji2]

The major problem with outboards is that they don't lower deep enough to allow reliable, strong thrust in anything but flat water.

I used one with 3 shaft extensions. What I gained from the outboard was to learn to sail in most restricted maneuvering situations where many people motor and in calms I just learned patience.

Secondly, they're nowhere nearly as reliable; they just aren't. I've spent years working with rhibs outfitted with multiple outboards in a commercial setting. The reason for multiple outboards is to maintain propulsion when one unit dies.

The real advantages are less initial cost and simplicity.

[Randy]

Magenta,

A 2cyl is slightly smaller and lighter but less power. I think Beta's being a Kubota are a smoother running, higher quality engine than Yanmar but don't have hard stats on that.

[Cadence]

Originally Posted by magentawave

I PMed Mark Johnson (he built and cruises his Searunner 34) a couple times and he recommended the 3 cylinder 20 HP Yanma. He said it would cost about $10,000.00 IF I did everything myself. Aaargh. Why do you recommend a 2 cylinder Beta verses something like the 20 HP Yanmar?






Thanks for the links. Are the OB's all the way down in those photos? If so, it looks like the props are barely below the waterline. I guess your thinking was that the OB's would be good for smooth and glassy conditions with no waves only, like in a calm harbor, right? Are those long shafts? What HP?






Downside to OB's is that over time fuel costs will be a lot higher than a diesel, but I sure like the simplicity of OB's and having less thru hulls! The only way I could see an OB working properly on a Searunner 34 in rough conditions would be to bring it as close to amidships as possible and get the props down really low. Jim Brown accomplished that when he retrofitted a sled on his 31. The 34 though is so much bigger and heavier than the 31 and has a lot more windage. Anyone heard of an OB sled on a Searunner 34?

I had a SR31. With a 15HP Honda 28 inch leg, hung on the stern it worked great. We are speaking sail boats. Who is going to be motoring in heavy seas?

[magentawave]

Originally Posted by Cadence

I had a SR31. With a 15HP Honda 28 inch leg, hung on the stern it worked great. We are speaking sail boats. Who is going to be motoring in heavy seas?

I'm a rag sailor for sure and pretty dang good at it too so I only resort to firing up the engine if I absolutely need to. The SR 34 I'll be checking out is in Canada now and IF I buy it then I'm thinking with all the windage and weight of the 34 that it might be nice to have a motor for maneuvering in tight harbors, etc. Another scenario... Mark Johnson has a Yanmar in his SR 34 and he said he can pinch a few degrees higher under sail with the engine on which comes in handy when he's trying to get into a strange port before dark.

IF I buy this boat and IF I install a diesel then I'm trying to figure out ways to do it as cheaply as possible. (Cheap as in save money and NOT cheap as in buy crap parts.)