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Old 21 April 2009, 08:45   #1
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Country: UK - Scotland
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Water getting over transom

Ok so I got my new engine a 9.9hp yamaha 2 stroke for my 3.50s zodiac. Went to loch lomond at the weekend with my youngest daughter to try things out. I'm only 11.5 stone and shes about 4.5 so not alot of weight, don't know what speed we got up but quick enough for my purposes.

The only problem was at WOT there was quite a bit of water coming over the transom just above the motor mount. I tried the "self bailer" it did not seem to have much effect. I had to stop now and again to bail by hand. The more water that got in the more it came towards the back of the boat i.e me 11.5 stone the motors 35kgs plus the weight of the water. The bow would lift quite high before it would plane until I bailed it out.

The sib is rated for a 20hp so the engines not to heavy for it can anyone shed any light on what the problem might be. The motor is short shaft.
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Old 21 April 2009, 09:57   #2
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Water over transom

It might be worth altering the angle of the outboard relative to the transom. You can get water pluming in over the stern if the angle is too close or too far from the transom. Generally it happens if the outboard leg is set too close to the transom, but you do say that the bow lifts high before you get on the plane, so it could need moving closer! Easy to do, though, so it's worth fiddling around. If that doesn't work you might need to invest in a set of fins for the cavitation plate........
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Old 21 April 2009, 10:18   #3
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SIBs can be quite sensitive to weight distribution. You want as much weight as possible towards the bow until she's on the plane - then come back aft.
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Old 21 April 2009, 11:41   #4
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I noticed on my old SIB (Achilles) that the one way valve wasn't. The water would seep in and hide under the floor until you accellerated, when it would all pool in the back, causing the bow high attitude you described.

My "normal" mode became to leave the plugs in unless I needed to drain water (from dive gear and divers, or the occasional wave over the bow.)

jky
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