Cavitation/Ventilation/Blow out depending where in the world you are reading this from....
Having a major problem on our tender, which we also use for fun on the rivers. Until yesterday we had been using a Johnson 4hp seahorse, which while usable, was a little sluggish and didn't have the power to get us on the plane. Took the plunge on Friday and bought a new Honda BF10she which I hasten to add, is very impressive in many aspects (will write another thread on that soon)
Anyway, Got out yesterday for the first with the new engine. After a couple of hours breaking it in, we decided to see how it would perform at speed.. Boy was I disappointed! Not because of the engine, but because of very bad cavitation problems. Boat is fine to around 8mph, sometimes even 10mph, but as soon as we hit this speed, the engine starts to race and propeller seems to loose grip, then speed drops back to 6-8mph and throttle has to be closed to get the grip back.
To me, when I look over the transom it looks like the prop is "digging a hole" in the water at the back of the boat. (Will try to get pics today)
When sitting stationary the cavitation plate is approx 2" below the water line, however once on the plane it is actually slightly above the water line. It does seem to be doing it's job to a degree, as there is water being thrown up, which it is deflecting back towards the prop.
I have read quite a lot of postings on various forums when I returned home last night, however none really are asking this exact question.
Boat: Wetline 310AR (3.1m with Air Floor)
Weight distribution: One person sat between the seat and bow, another at the tiller (slightly behind seat, sat on tube)
Prop: 9-1/4x9p (standard) 4 blade
Trim: Tried all settings, mid point seems to be best but still nowhere near perfect
Would propping up (or down) help? Honda make props varying from 9-1/4x7 up to 9-1/4x11 in 1" increments for this engine.
Doing the math, I would say it should be capable of more like 18mph?
Any suggestions welcomed
Pete
Having a major problem on our tender, which we also use for fun on the rivers. Until yesterday we had been using a Johnson 4hp seahorse, which while usable, was a little sluggish and didn't have the power to get us on the plane. Took the plunge on Friday and bought a new Honda BF10she which I hasten to add, is very impressive in many aspects (will write another thread on that soon)
Anyway, Got out yesterday for the first with the new engine. After a couple of hours breaking it in, we decided to see how it would perform at speed.. Boy was I disappointed! Not because of the engine, but because of very bad cavitation problems. Boat is fine to around 8mph, sometimes even 10mph, but as soon as we hit this speed, the engine starts to race and propeller seems to loose grip, then speed drops back to 6-8mph and throttle has to be closed to get the grip back.
To me, when I look over the transom it looks like the prop is "digging a hole" in the water at the back of the boat. (Will try to get pics today)
When sitting stationary the cavitation plate is approx 2" below the water line, however once on the plane it is actually slightly above the water line. It does seem to be doing it's job to a degree, as there is water being thrown up, which it is deflecting back towards the prop.
I have read quite a lot of postings on various forums when I returned home last night, however none really are asking this exact question.
Boat: Wetline 310AR (3.1m with Air Floor)
Weight distribution: One person sat between the seat and bow, another at the tiller (slightly behind seat, sat on tube)
Prop: 9-1/4x9p (standard) 4 blade
Trim: Tried all settings, mid point seems to be best but still nowhere near perfect
Would propping up (or down) help? Honda make props varying from 9-1/4x7 up to 9-1/4x11 in 1" increments for this engine.
Doing the math, I would say it should be capable of more like 18mph?
Any suggestions welcomed
Pete
