Cavitation problem?

[wokii1]

Thanks everyone agian for your replies,

I found the motor install paper work and it suggests the cav plate be installed level or upto 25mm below. Also found the outboard operation maintenance & warranty manual but there is no info on prop selection in it.

@ Cormorant , you are prob right about the board, it is the third motor in the life of the hull, all dealer fitted. So there are prob lots of holes hidden behind it, but in saying that I cannot see any from inside.

I rang wondall rd marine today about my problem (Can't remember who I spoke to but they knew what they were talking about and were very helpful), I asked about cav plate height and prop size. After I told him my motor type and hull he knew the motor would be mounted as low as it could be and the cav plate would be a touch higher. They said many cruise craft hulls require wedges about 20mm to pack out the motor mount at the top away from the transom so the motor tucks under more. He also said that by the wot rpm I've got it sounds like it right.

I also spoken to a mate that knows quite abit about these things , and he was out in my boat with me when I ran the se200 and couldn't trim it enough without ventilation. When we got back to the ramp that day we had a quick look at the motor height ect but couldn't see any obviouse problems, that is why I post it here. But today I told him about the chunk of bog I found and his money is thats the problem, and that he never really thought of that sort of thing as my hull is pretty tidy. Because I can't really drop the motor any lower on the transom he suggested a jack plate may also solve my problem. Anyone had any experinces with jack plates?

The plan atm is flip the bolts and finish cleaning up the bog repair at the back, and next weekend I'll taking it for a run and see how it goes. I'll update when I can.

[cormorant]

If it is not leaking don't flip the bolts. They are correct as is.

Wedges are common when you run out of trim in and may work but in the end it is all about how the boat rides Tucking in the motor makes the full length of the hull work ( softer ride ) and with boats that have a fine entry they wil be smoother into a chop that way but wetter depending on hull flare at the bow. You don't want it trimmed in running down swells as you will possibly sumbarine the boat or end up in a trough and push a thousand ton of water. Better to have it trimmed up so the bow lifts out of teh trough and you keep some way on.

The not so sharp trailing edge on that hull is what also doesn't help but that is the way they come out of the mould.

Jack plates. They move the motor back 6-12 inches and as you go back further the water height flowing off the trailing edge of the hull increases ( ie same as dropping motor ) but obviously it means you don't chop the transom. It means the motor weight is further outside the transom and that can change the way a hull handles . Others when replacing motors go for the longer shaft and and raise the existing transom ( not as much as the increase in shaft length)

If the cav plate addition makes it worse get rid of it. The only ones of those I like are teh permatrim and only when there is a issue to fix.

[marto78]

Seeing as how you cant lower the motor any further you may benefit by getting a four blade prop which will give you more bite in the water and should stop the cavitation issues. Try giving the guys at Solas Propellars a call and see what they recomend.

[wokii1]

Thanks everyone for your help,

This week I sanded the repair I found under the transom, flowcoated it, and sanded it again. I also flipped the bolts on the se200 sport so the heads are down.

Went for a run in the boat this morning out from cleveland to harries. (didn't catch much ) It was abit choppy but still got to give it a good squirt.

That chunk of bog was the problem.

I can now trim just over half the gauge (2 bars).

This is one bar more trim then before I installed the se sport and one & a half bars more than after I installed the se sport.

Some extra info, I got 54 km/h on my gps at 5800rpm with 2 people n fishing gear. ( speed gauge said 37mph but it is prob wrong. )

It has been said that the cav plate be in the water while on the plane. I checked this as well and the cav plate is just out when trimmed 2 bars, does this mean I should trim a little less?

Here is a picture of the motor angle / trim at 2bars. Attachment 69303

[stue2]

Thanks everyone for your help,

This week I sanded the repair I found under the transom, flowcoated it, and sanded it again. I also flipped the bolts on the se200 sport so the heads are down.

Went for a run in the boat this morning out from cleveland to harries. (didn't catch much ) It was abit choppy but still got to give it a good squirt.

That chunk of bog was the problem.

I can now trim just over half the gauge (2 bars).

This is one bar more trim then before I installed the se sport and one & a half bars more than after I installed the se sport.

Some extra info, I got 54 km/h on my gps at 5800rpm with 2 people n fishing gear. ( speed gauge said 37mph but it is prob wrong. )

It has been said that the cav plate be in the water while on the plane. I checked this as well and the cav plate is just out when trimmed 2 bars, does this mean I should trim a little less?

Here is a picture of the motor angle / trim at 2bars. Attachment 69303

If it worked without all the dramas you've had before then it's right. If it cavitates a little every now and again follow marto78 advise. There will be a prop to fix a little cavitation. Glad to hear it was an easy fix. The cav plate on all my boats are set just on the water. Look up the verado club you will see what it looks like. www.veradoclub.com/smf/index.php?topic=137.0.

Cheers, Stu