Yamaha 130 2 stroke height

[maineiac5586]

1997 wellcraft 190ccf center console. 2001 yamaha 130 v4 20 " . Noticed a good deal of porpoising and I can only trim up not even 1/4 ot the trim guage. Also seems like a lot of spray ( whole back of the boat gets wet after running). I can't go back and see where the cav plate is when planing and don't have anyone to help me check that. Cav plate is about 1 1/2 " above bottom of boat. This boat uses a stepped transom with approx 7 " setback. I tried trimming up above 1/2 guage and didn't get any cavitation. I'm ready to move up a hole on the engine mount. Will 1 hole make enough change?

 

[99yam40]

Moving up one hole is not that hard to try,
but I do not understand what you mean you can only trin 1/4 on the gauge, but can trim 1/2 with no cavitation.
seems to me if it is porpoising at 1/4 it must be going nuts at 1/2.

maybe you need tabs or a tail to keep the bow down or transom wedges to change pitch of the motor

 

[maineiac5586]

Moving up one hole is not that hard to try,
but I do not understand what you mean you can only trin 1/4 on the gauge, but can trim 1/2 with no cavitation.
seems to me if it is porpoising at 1/4 it must be going nuts at 1/2.

maybe you need tabs or a tail to keep the bow down or transom wedges to change pitch of the motor

If the water is nice and flat I can trim up to about 1/2 on the guage but it's rarely flat and calm.

 

[Kola16]

Tape your phone to a stick, tape the stick to the back of your boat, and record the cavitation plate. Or just move it up 1 hole. Although the height sounds about right to me.

How is your weight distribution in the boat? Gas tanks? Batteries? Anchors? Etc. Too much weight in the back and nothing in the front can cause porpoising.

 

[maineiac5586]

Tape your phone to a stick, tape the stick to the back of your boat, and record the cavitation plate. Or just move it up 1 hole. Although the height sounds about right to me.

How is your weight distribution in the boat? Gas tanks? Batteries? Anchors? Etc. Too much weight in the back and nothing in the front can cause porpoising.

I picked up a waterproof camera and going to get a long selfy pole to get some video of the plate.i have a 50 gal built in fuel tank located under where I sit. Not much for weight up in the front except the anchor. I guess I could throw some weight up in the anchor locker. Maybe something kind of flat and heavy? I'm going to check the video and optimize the height and after all that is set I'll pursue the weight option. Thanks

 

[Kola16]

I picked up a waterproof camera and going to get a long selfy pole to get some video of the plate.i have a 50 gal built in fuel tank located under where I sit. Not much for weight up in the front except the anchor. I guess I could throw some weight up in the anchor locker. Maybe something kind of flat and heavy? I'm going to check the video and optimize the height and after all that is set I'll pursue the weight option. Thanks

That's the best option. Get the video before anything else. Sounds like your weight distribution is fine, just something I thought to throw out there. Adding weight usually isn't the solution to porpoising anyway, it would better be solved by moving weight. Again, I don't think that is your issue. A video of how much your boat is trimmed up on plane before you start porpoising would help too.

 

[maineiac5586]

That's the best option. Get the video before anything else. Sounds like your weight distribution is fine, just something I thought to throw out there. Adding weight usually isn't the solution to porpoising anyway, it would better be solved by moving weight. Again, I don't think that is your issue. A video of how much your boat is trimmed up on plane before you start porpoising would help too.

I currently have a hydrofoil on the cav plate. Do you think I should remove it for the video test?

 

[Kola16]

That's a good question. I have never been a fan of hydrofoils for myself simply due to drag. With that said, I do not know much about them besides they can give a better hole shot and lower planing speeds. I would probably take it off for the video so it will be easier to see, but hopefully someone who knows more about them can chime in. Video with both if you have spare time. All those hydrofoils perform differently.

 

[maineiac5586]

That's a good question. I have never been a fan of hydrofoils for myself simply due to drag. With that said, I do not know much about them besides they can give a better hole shot and lower planing speeds. I would probably take it off for the video so it will be easier to see, but hopefully someone who knows more about them can chime in. Video with both if you have spare time. All those hydrofoils perform differently.

I'm planning on it. Took tomorrow off got myself a nice camera on a pole for video. Bringing another prop and tools to remove hydrofoil if needed. Stay tuned

 

[maineiac5586]

Tried it 1 hole up (2nd hole down from top). Big improvements but still didn't see cav plate in video. Wound up moving it up another hole ( 3rd hole down from top). Cav plate visible in video. No prop blowout on turns. Only thing is I noticed a v spray of water out to each side of the motor when on plane. This v spray was actually bigger on the higher positioning of the motor. Was less when I was 1 hole lower but no cav plate to be seen. My boat has about 7 inch setback for the motor to mount. Looks like the ribs above the cav plate line up more with the bottom of the setback maybe that's what's making a bigger v pattern? I guess I'll leave it in the 3rd hole ( higher position) and not worry about the v spray?

1st pic is 3 holes from the top. 2nd pic is 2 holes

 

[maineiac5586]

So I'm thinking the v spray ( v like spray coming from each side of motor) is coming from that ribbed section above the cav plate seen in the front of the outboard. With the motor mounted in hole number 3 during testing the v spray was worse then when mounted in hole number 2.
For this discussion mounting holes are 1 through 4 with 1 being at the top.
Couldn't see cav plate when on plane when mounted in hole # 2 but less v spray. Mounted in hole 3 cav plate now visible on plane but v spray worse. So live with the spray and leave it in the higher position where cav plate is visible or lower it down for less spray but cav plate not visible? For testing it was me by myself and about 25 gal fuel.

 

[99yam40]

when the cavitation plate is above the water, I do not see how anything above it would be causing water spray.

if you really want to know for sure take that sacrificial anode off and run it to see if that makes it go away.

might check on props that have more stern lift,

I would think taking off the foil might cause even more problems with proposing.
have you even run the boat without it?

 

[Kola16]

Hole 2 when the cav plate/foil was not visible is definitely too low. The hole 3 position looked pretty good and if the prop did not wash out when you turned, then I would say definitely do not move it lower than 3.

 

[maineiac5586]

when the cavitation plate is above the water, I do not see how anything above it would be causing water spray.

if you really want to know for sure take that sacrificial anode off and run it to see if that makes it go away.

might check on props that have more stern lift,

I would think taking off the foil might cause even more problems with proposing.
have you even run the boat without it?

I tried it without it and it was worse. Lot more bow rise and more sensitive to porpoising.

 

[maineiac5586]

Hole 2 when the cav plate/foil was not visible is definitely too low. The hole 3 position looked pretty good and if the prop did not wash out when you turned, then I would say definitely do not move it lower than 3.

Thanks. Yeah no prop wash out. I took tight turns without an issue.

 

[maineiac5586]

when the cavitation plate is above the water, I do not see how anything above it would be causing water spray.

if you really want to know for sure take that sacrificial anode off and run it to see if that makes it go away.

might check on props that have more stern lift,

I would think taking off the foil might cause even more problems with proposing.
have you even run the boat without it?

Seems strange that the anode would cause a bigger v spray at the higher engine mounting position? Do you think maybe the water coming off the bottom of the hull is deflecting off that ribbed section of the motor?

 

[99yam40]

how does the water get to that if it is not getting to and going over the Cav Plate
take it off to see for your self

 

[maineiac5586]

how does the water get to that if it is not getting to and going over the Cav Plate
take it off to see for your self

Ok I'll try that. Thanks