Trimaran - Especially Searunner - Owners

[md7a]

Does anyone have experience with a kort nozzle on a trimaran outboard? I am hoping to get better low speed power from my out without adding weight.

[Cormorant]

Will, I researched the PropGuard all over the web this spring, and never came to a conclusion. . . . The manufacturer claims increased thrust etc., but some users were disappointed and seemed to imply the thing was a gimmick. But I think many of those were bass-boat fishermen using it at planing speeds.

I wound up not buying one, but am still considering the possibility. Would love to hear some real-life experiences from sailboat owners.

On our boat (not a trimaran), it would serve a dual purpose of increased thrust, plus protecting our transom-hung rudder, which sits near enough to get dinged when motoring. And a third bonus -- protection for anyone who goes swimming, on purpose or not, near the prop when it's turning. . . .

[jannpage]

Get a prop with a larger surface and lower pitch if you want more pulling (or backing) power. Yamaha for ones build high output motors in the small HP size( 9.9 or so) that have lower gear ratios and swing bigger props with a lot of surface and boy to do they deliver low speed power. About like my little 16Hp 4 wheel drive tractor. In low/low you cannot stall her even at modest throttle setting and lots of weight on all 4. Its all in the gearing and the prop size and shape. I think almost all advertising is a bit like political propaganda. What is amazing is the exten educated people are willing to die for propaganda. I guess they put the critical thinking part of their brain on park. Makes it relatively easy for those that are a little less naive.
Cheers

[Mark Johnson]

Originally Posted by jannpage

Get a prop with a larger surface and lower pitch if you want more pulling (or backing) power. Yamaha for ones build high output motors in the small HP size( 9.9 or so) that have lower gear ratios and swing bigger props with a lot of surface and boy to do they deliver low speed power. About like my little 16Hp 4 wheel drive tractor. In low/low you cannot stall her even at modest throttle setting and lots of weight on all 4. Its all in the gearing and the prop size and shape. I think almost all advertising is a bit like political propaganda. What is amazing is the exten educated people are willing to die for propaganda. I guess they put the critical thinking part of their brain on park. Makes it relatively easy for those that are a little less naive.
Cheers

The 9.9 Yamaha 4 stroke "sail drive" model, is exactly as stated. It has unbelievable thrust for it's size! On my previous tri, a SC 28, this kicker could power it @ 10 knots when lightly loaded. I recommend it highly...

Mark

[Cormorant]

[Sorry if this is thread drift by a lowly mono-sailor, but I figure some trimaran sailors wonder about this stuff, too. . . . For the record, I dream of someday having a SeaRunner]

For those of us not blessed with Yamaha HT motors, we have the choice of optimizing what we've got, or selling what we've got and buying a Yamaha. For now I'm trying to optimize what I've got, which is a 4-stroke Nissan 9.8 HP. It's a great little motor, never misses a lick, and gets 13 nm/gal (about 15 statute mpg) when in calm seas going ~5 to 5.5 mph.

It came with a 8.9" diameter, 8" pitch, 3-blade prop. For a spare I bought a 4-blade 7" pitch prop, but I haven't tried that out yet.

I once queried a Nissan dealer about the optimum high-thrust prop for our boat, which weighs about 4500 lbs. loaded, and this is his reply:

"4500 is pretty light so you might try the original standard prop first to get an idea. Every boat performs differently but going down to the 5" pitch would be a pretty big drop from the 8". 4-blades are better for thrust, especially in reverse. Most people do not go all the way down to a 5 but instead pick a happy medium. The 6.5" 3-blade is very popular as is the 7" 4-blade. Going all the way down to the 5" pitch will give you the highest RPM's but also the worst fuel economy." [my bolding]

So his email got me wondering about the trade-off between thrust and fuel economy. I do love the mileage we get right now, and am hesitant to mess with it. But I suppose I should try a full season with the 7" pitch, 4-blade prop and see what sort of mileage we get, versus speed, power, etc.

I still like the idea of those PropGuard kort nozzles just to protect our rudder. . . .

[Jmolan]

We wrapped a kort nozzel around a 90" new generation wheel. The tips are 1" thick foil shaped (viewed from the ends)

Just having some fun! The new generation wheel was a HUGE improvement.

I use a 9.9 Yamaha on my 34' Searunner, and it supplies plenty of power. I have no complaints. Never felt a need for a nozzle, but it would not hurt I am sure!

I am in Mexico now, my boat is for sale. (34' Searunner) I will be launching it soon, to be on a mooring in front of the house.

Also there came up a Marples 44' for sale. I always liked this boat!

1998 Custom Marples Trimaran Sail Boat For Sale - www.yachtworld.com

[Cormorant]

That's just the sort of prop I want on my boat!

So you're selling the SeaRunner with all that cool Dynex Dux rigging?

[smj]

We repowered our old Cherokee with a Honda years ago. After a few months of use we purchased the old Handler kort nozzle and installed it. What a huge difference! It gave us a huge amount of thrust and cut our fuel usage by about 30%.

[Boatguy30]

I went over to have a look at the CC 44 on Wednesday and the broker was writing up a contract on it when I walked in his office! The boat looks good from the dock, but is huge. Beam is 28.5' so no worries for full-time cruising in the islands, but where do you put it when between cruises?

The PDQ cats came stock with the Yamaha hi-thrust motors, but lately a lot of guys have been repowering with Hondas that come with the standard gear ratios and a 4 blade SOLAS style prop. They find the performance rather the same, perhaps the the low end is better with the Yamaha. The main issue with especially the older Yamahas is keeping them running well at idle to keep the prop spinning. The actual gear ratio difference is slight. I think stock is 2.08:1 and the "high thrust" is maybe 2.5:1.

Cheers,
Jeff

[clemon]

Hello all,

I've got a Searunner 34 with a pretty good sized doghouse. The doghouse is great from a comfort point of view, but not so great for windage effects. Between windage, and getting pushed around by tidal currents down here in Auckland, getting into tight pile moorings is too exciting for my taste. I did some quick math and verified that if I lined everything up perfectly, I had about 3seconds to get at least two lines on the boat before drifting into the barnacle encrusted posts. I'm ahead, but the barnacles have gotten some hits too.

I think that some of the close quarters work would be less exciting if the boat had quicker response at low speed. I'm thinking of making the rudder slightly larger at the next haulout to get faster low speed response in forward and reverse. Has anyone else tried this? This will probably be a small extension on the rudder trailing edge. I don't use the servo tab wind vane, so I can modify the back of the rudder without interfering with any other systems.

On a vaguely related note, same boat, I've got a fixed three blade prop now, and am planning on going to a kiwiprop feathering three blade. I'm guessing this should make tacking quicker and gain about a knot or so of average speed. Has anyone done a similar swap and checked the results?

Thanks for the info.

Cheers,

Chris

"So much deck area, so little time to paint."

[jannpage]

Conversion to a Kiwi will of course improve sailing speed. I particularly noted a great improvment under light winds, tacking and windward. I could make so much better progress under those circumstances than before that I uses the engine far less.
But the real surprise was backdown/backup power. It was wonderfully improved . You may find those barnical infested pilings will be far less threatening because you may be able to approch them in reverse.
What engine are you running?

Regarding the Honda/vrsYamaha 4 stroke 10 hp engines. I have owned both - both were 89's. Both were wonderfully dependable engines. Ran forever. and idled like a tank. Of course I avoided 10% ethanol fuel like it was the poison which it is to all 2 stroke engines and 4 cycle air cooled yard tools . In 12 years in Europe, I did have to clean the Honda carb once to straighten out the Idle. My Yamaha is here in the states and I am careful about fuel. My only beef is they are heavy. The Honda was on a Crowther tempest enlongated to 37ft. The Yamaha is an a 24ft Woods Strider Club Cat here in Pensacola.

Cheers
Lloyd

[Boatguy30]

Chris-

Which boat do you have? There was a SR 34 for sale at Bayswater earlier this year. I believe that boat has a modified rudder as you mention. I owned for only a short time the S Island built SR 34 that ended up in Nelson. (I believe there are 3 SR 34s in NZ) That boat is now up near the top in of the Gulf there somewhere north of N Shore City. The guys name is Mark and I know he is planning to do some changes to the rudder and centerboard. I can get you his email.

I will be in Auckland in March visiting Mark and would be keen to see your boat and have a sail. I've just made an offer on another Marples tri, so may have another boat myself by then.

Cheers,
Jeff

[Mark Johnson]

Regarding two previous posts...

Finding dockage for wide tris is indeed more of a challenge, but usually it can be found. Unfortunately, half of the 16 years that Delphys has been launched has been tied to a dock, in order to finish or refit the boat, and / or make a living...

We have lived up and down the US Eastern Seaboard, including the FL Keys, and always found a situation somewhere. Sometimes it was a shallow but super wide slip where a middle piling had been broken off, side to, or side to on a "T" head. We have also been side to in a canal, and once had private dockage in a bayou. You just have to shop around a lot more! BTW, we never paid extra...

I would not make a larger rudder, It won't hurt much, but it wont help close quarter maneuverability either! Switching from a skeg to a spade rudder WOULD help close quarter maneuverability, but you would loose too much, as far as a Searunner's legendary seakeeping ability is concerned, IMO.

PROPS... Size for size, (with "size" = to the total square inches of exposed blade surface), as is the industry standard, a two bladed prop is far more "efficient" than a three, and a three more than a four, etc. The ONLY reason so many drivetrain set ups go with more blades, is when there is not room, or it becomes impractical to have the larger diameter of a "same sized" two bladed prop. (We use a 15", two bladed, folding prop on our 34)

The "Flex O Fold", that we use, is the forward thrust champ, according to test comparisons done by MIT, (even compared to other folders, a Max Prop, OR a fixed prop). The Flex O Fold is really slick under way, and when we come into the dock @ 1 knot, it will still stop the boat dead in the water, in 4 or 5 more feet, after hitting FULL reverse. I recommend the "Flex O Fold" highly.

After stopping the boat several feet from the dock, (side to)... we each use a boat hook and reach out to the super flexible "regatta braid" dock lines, that we have tied in and ready, gently looped from the TOPS of the dock's tall pilings. With the boat now stopped, we use these lines to pull the boat sideways to the dock.

With our slip being in a small recession in the bank, and the face dock only about the length of the boat, we can't just motor up and step off, so we come in at a bit of a diagonal, stop the boat dead, and use the waiting coiled dock lines as described. For the aft = (further out) end of the boat, my up to 14' long telescoping boat hook comes in handy, in bad landings on a windy day.

If you have the depth, I'd come in with the CB at LEAST half way down. More than anything else, this will cut your close quarter maneuvering circle in half!

Under these circumstances, as well as sailing in general, ALWAYS use a "fuse" to hold the CB down. Simply crank it down to the desired position, and tie a 3' piece of 1/8" parachute chord to the CB's down line using a "rolling hitch", just before the winch, on the loaded part of the down line. Then stick the other end of the parachute chord into the sturdy cam cleat positioned on the mast, and remove the 3/8" down line from the winch. This way, if you have the ("rubber hose bumper" as designed) in the trunk, and hit the bottom or any soft obstruction, the 1/8" line pops and the board comes up undamaged. The exception is if motoring backward!!! You are then VERY vulnerable to major damage if you have the board down and hit the bottom. DON'T LET IT HAPPEN!

Happy Searunnin...

[PhantomBoatwork]

Any experience with the Martec prop? I got one in good shape for my CC44 (under coinstruction) and shipped it off for refurbishing. It's 18" with a 14 pitch. Doesn't appear to have been used much at all.

[Mark Johnson]

Originally Posted by PhantomBoatwork

Any experience with the Martec prop? I got one in good shape for my CC44 (under coinstruction) and shipped it off for refurbishing. It's 18" with a 14 pitch. Doesn't appear to have been used much at all.

The newer "geared" Martecs are a contender, but not quite as efficient as Flex O Fold. (Certainly, "good n uff"). The older NON geared ones flop and clank too much for me.

Prop size... complicated subject.
Getting the size and pitch "just right" for the engine is quite a trick, close is not. Engine and prop manufacturers are a good resource. One advantage of buying new, (like a Flex O Fold), is that you come as close as you can, and go for a test run. Then if your dealer is a nice guy, he will let you swap out for different pitch blades. (Like, within the first week)! The extra haul out is worth the money!

Ideally, you want the engine, in fwd gear, to JUST be able to reach FULL short term RPM. (3,600 RPM for our Yanmar 2 GM 20 F) Close is OK, but it is much better to be slightly under propped, than over, at least as far as engine life is concerned.