kitjv
Junior Nomad
Posts: 98
Registered: 12-13-2006
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Outboard Motor Stabilizer
Hopefully someone can help me with this problem. I have a new 12-ft. inflatable boat with a 20HP outboard. The boat gets up on step & planes very
easily. However, when the throttle is opened beyond about 1/2, spray from the prop washes over the transom regardless of how the outboard is trimmed.
I assume that the spray is caused by the prop being partially out of the water at speed.
Question: Will an aftermarket stabilizer solve this spray problem?
As usual.... thank you for your wisdom.
Kit
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Cypress
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Registered: 3-12-2006
Location: on the bayou
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Mood: undecided
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Maybe too much motor for the boat? Wrong prop?
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capitolkat
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Posts: 510
Registered: 3-9-2006
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check the link below
On anticavitation addition-- I think you'll find your answer there--
Life is too short to drink bad wine
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Diver
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Registered: 11-15-2004
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I run a 9.9 on my 10 Zodiak.
The 20 is probably a bit more than you need but should still work.
Make sure it is trimmed tight against the boat and if this doesn't help, get a shark fin or other anti-cav device. They work great on small
boats/motors.
.
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Diver
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Almost all 12' inflatables will use a short shaft motor (15").
A long shaft used on one of these would create extra drag and probably splash also.
I run a 2-stroke short shaft to keep the weight down and the "git-up" up !!
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kitjv
Junior Nomad
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The outboard is a short shaft & the inflatable has a 15" transom height. My initial thought was that the shaft was sitting too low in the water
causing drag. At speed, this would cause water to be pushed up over the transom.
However, at planing speed the motor's built-in anti-cavitation plate seems to be right at water level. So shaft drag is not the problem.
As speed is increased, a point is reached when spray from both sides of the shaft shoots upward deflecting off of the protruding side tubes & into
the boat.
I really need to run the boat again & try to note where the spray is coming from. But if anyone has any other thoughts or suggestions, I'm all
ears!!
Thanks, everyone.
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Diver
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Registered: 11-15-2004
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12' soft boat, 15" transon height.
1) Check the boat for tears or rough spots on the bottom near the transom.
2) Check that you have the right prop for the motor.
3) Set the motor angle tight to the transom.
4) Try a Stingray or Doelfin hydrofoil.
Also, if you have a soft or platform bottom, make sure you are not collecting water below the floor. This will cause an internal "swell" that will
cause the boat to drag and create excess spray. With a 20Hp you my not notice the drag. Fix any leaks and pull the plug at speed if needed to get rid
of any splash water. Mine gets water below the floor when I am wet with wet gear from snorkeling, etc...
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kitjv
Junior Nomad
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Registered: 12-13-2006
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| Quote: | Originally posted by Diver
12' soft boat, 15" transon height.
1) Check the boat for tears or rough spots on the bottom near the transom.
2) Check that you have the right prop for the motor.
3) Set the motor angle tight to the transom.
4) Try a Stingray or Doelfin hydrofoil.
Also, if you have a soft or platform bottom, make sure you are not collecting water below the floor. This will cause an internal "swell" that will
cause the boat to drag and create excess spray. |
Thanks, Diver, for the suggestions. In response...
(1) No tears or rough spots - the boat is new.
(2) The outboard is new & the prop is the standard one it shipped with.
(3) I tried this but it didn't seem to resolve the problem at speed.
(4) I have an aftermarket stabilizer that I haven't installed yet. I wanted to first get a better idea specifically where the spray is coming from
& the likely cause.
The boat has an air floor & inflatable keel. Both were inflated to the recommended maximum pressure. It is surprising how rigid the air floor is.
No water had collected inside the boat.
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