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Old 28 February 2005, 14:20   #1
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Sternpower leg (New to forum & computers)

Hi Guys
I'm fitting a Yanmar into an Arctic (I know I should have looked on the forum first) with a sternpower leg. What's the best way to to run the exhaust, through the leg or through transom

Davie
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Old 28 February 2005, 14:38   #2
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David hi and welcome, all of the Pacifics I have seen have used a separate exhaust rather than through the sternpower which would exit at the bottom of the transom plate. There must be a good reason, just can't think of it. You could try a query to Halmatic or Lancing to see if there is a good reason.

A sternpower leg gets warm to the touch after an hour so anything that keeps heat away from those bearings by having a spearate exhaust might be worth thinking about.

Any chance of some pics of your conversion as it goes along ? sounds like a major bit of work

Pete
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Old 28 February 2005, 14:58   #3
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Hi David, there have been problems in the past with bravo 3 legs failing prematurely when coupled with 300 hp yanmars. You will find threads about this subject on this board.

The agents claim that when this leg is fitted into a rib, a lot of the leg is out of the water leading to overheating. And running the exhaust through the leg makes it worse. When fitted in a hardboat, the leg is deeper in the water.

I believe they are on top of the problem now with newer legs.
Nick.
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Old 01 March 2005, 02:25   #4
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Hi,

I spoke with the norwegian Yanmar dealer and the would not recommen a bravo 3 leg on a rib, the reason is that the props have almost no slip and therfore they brake more often than a bravo one that have more slip. this i s specially i rough waters where the props might get some air.

Allso driver showers is a must for keeping alow temp on the drive leg.

We have bought a 36 feet rib with twin yanmar 315 and we changed the bravo one x leg for the the stronger bravo one XR
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Old 01 March 2005, 05:06   #5
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Thanfully the sternpower leg doesn't have the exhaust going through the leg. Instead there is a letter box sized slot in the inside of the transom below the jack shaft which exits through the transom plate, but even so hot water mixed with exhasut gasses is going to raise the temp of the transom plate and therefore the bearing carrier.

David how big a Yanmar are you fitting ? The sternpower manual suggests the 101 is rated for about 175 hp. From the Manual

"A suggested limit of 350 lb-ft is given for normal use with the assumption that the engine has only minor torsionals."

T (lb-ft) = 5252 x HP / RPM

Hope this helps

Pete
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Old 01 March 2005, 14:18   #6
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Hi Thanks for your replys
I never explained very well that it's not a yanmar leg(bravo 1-2 or 3) but an ex navy Sternpower 113.But Petes reply sounds like good advice, so I'll take it out through the transom.
once we get on a bit I'll try and post some pics .
Thanks for your replys
Davie Pete it's 200HP
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Old 01 March 2005, 14:43   #7
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David, I think yours is a 7.5 hp / 100 rpm (depending on gear set), which means it will be slightly over powered at the working rpm. The 101 was generally 6.7 hp / 100 rpm. Put up some photos, the fibreglass work looked quite good on the transom.
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