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Boat porpoising. Horrible spray. I think I know the answer but dealer giving pushback

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Boat porpoising. Horrible spray. I think I know the answer but dealer giving pushback

Old 06-01-2021, 12:15 PM
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I’m sure someone else will have a comment on that prop , I don’t know much , but it doesn’t seem to have much grip.
Old 06-01-2021, 12:20 PM
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Easy to fix at home using a wood block under the trim fin, a socket set, some 5200, and the trailer tongue jack. If the Anti Ventilation plate is in the water or highly obscured by splashing when running trimmed out on a fast plane (Mid 4K RPM) then raise it up. Keep an eye on the engine temp while testing of course. I doubt any cavitation issues, and ventilation and grip loss are unlikely due to having a 4 blade stainless prop. I think dealers set them low so people don't complain about grip issues and they never have to worry about a customer coming back with low water pressure damage. Keep an eye on the engine temp while testing of course.

FYI I have my engine mounted all the way up on my boat (not that its the same) but it was second from lowest when I got it.
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Old 06-01-2021, 12:22 PM
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Originally Posted by Dacman View Post
Iím sure someone else will have a comment on that prop , I donít know much , but it doesnít seem to have much grip.
On a prior skiff I had I switched pitch and from a 3 to 4 blade. I loved it on that particular boat. I was happy to get a 4 blade stainless buuuuutttttt......different hulls, motors etc. I know a prop can be like a fat man trying to find the perfect pair of jeans(ask me how I know 😀 )
Old 06-01-2021, 12:30 PM
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Not the best picture to judge, but it almost looks like a 25 inch engine on a 20 inch transom. Not that it would matter, but is that a counter rotating engine spinning the prop counter clockwise.
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Old 06-01-2021, 12:33 PM
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Originally Posted by jcush87 View Post
easy to fix at home using a wood block under the trim fin, a socket set, some 5200 4200, and the trailer tongue jack. If the anti ventilation plate is in the water or highly obscured by splashing when running trimmed out on a fast plane (mid 4k rpm) then raise it up.
fify
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Old 06-01-2021, 12:42 PM
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Raise the motor and add some lenco trim tabs. The tabs will help big time. You should not overheat by raising the motor. The water pickup should be in the nose cone of the lower unit.
Old 06-01-2021, 01:02 PM
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You can't tell a thing from that pic.
Old 06-02-2021, 05:19 AM
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The sales manager took the boat out yesterday. He had concerns and the motor is sliding up 2 holes today now. He's taking it back out today too. He recognized how bad the spray was. I am a little concerned that after reading all these posts and seeing the exact same comment every article I read, that they're not checking the level of the AV plate that is mentioned almost in unison here. I can't wait to get back to town and do that little test myself and see where it is even after being raised.

The sales manager is likely concerned about selling these boats for cape craft and their specs are off that bad. This is the manufacturers recommended height.

Ill have to post about my experiences with Cape Craft in just the first few weeks once everything is done. Their specs on other items are an issue and their QC is questionable. I'm also waiting on an email response for 2 weeks now on another issue.
.
hopefully this takes care of this issue and we can move on. The other items are minimal but sure breaks my trust with them.


Originally Posted by karlow View Post
You can't tell a thing from that pic.
yup.....this why I had admitted that when I posted it and in 2 other posts after. Thanks.
Old 06-02-2021, 05:30 AM
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Originally Posted by jcush87 View Post

FYI I have my engine mounted all the way up on my boat (not that its the same) but it was second from lowest when I got it.
I have done the same, porpoising and top speed got heaps better. Unfortunately I got issues in larger seas with grip. The prop would vent in following seas and in corners. Then I've put it one hole down: no ventilation anymore, but extreme torque steering during acceleration (despite hydraulic steering).

My point is: you gonna have to find the perfect setting for your boat and for your usage. The only way to do it is to try. I'd ask the dealer to set it two holes up and that you tell him you'd come back if you'd ever get a temp alarm. How do you know stuff if you don't try?
Old 06-02-2021, 05:36 AM
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Since you own it, put on a hydraulic jackplate and reap the benefits.

Or you can screw with it endlessly.

Nothing can be told from that pic perspective

unusual hull shape, could trap air and aerate the water quite a bit to prop. Running motor down should not result in massive spray.....more drag ....sure.



Last edited by mbb; 06-02-2021 at 05:45 AM.
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Old 06-02-2021, 05:49 AM
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As you go up in height, first thing you'll notice is some prop slip in tight turns. Then as you go higher it might slip a little while planing off, or in rough water, and you will eventually have high slip numbers at higher speeds. All that happens before you will get it high enough to lose water pressure. Which you can at least monitor via the telltale if you don't have a gauge for it. I can't imagine that within the range of the factory clamp you can get it high enough to lose water pressure.

For speed boats we measure the same way, but it is hull bottom relative to propshaft centerline instead of the a/v plate. When you get that high you need to worry about water pressure, or get a low water pickup.

2 holes up is a good start. Other potential causes for porpoise are
-trim tabs mounted too low (doesn't look like you have them)
-weight distribution too far aft
-hook in the bottom of the boat. Put a long straight-edge over the last 6-8' of the boat and see how straight the hull is
Old 06-02-2021, 05:50 AM
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Raise motor 2 holes and see what happens, no biggie, easy to do at home using trailer jack and blocks of wood....
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Old 06-02-2021, 06:02 AM
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Why is that a left hand (counter rotation) Lower unit? Sure looks like a left hand prop.
Old 06-02-2021, 07:32 AM
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Originally Posted by haystack View Post
I imagine this is just hard to even discuss generically without photos. I knew that and should have done that before I dropped it off. I guess I was so convinced that was the issue.
Unfortunately I realize the below picture is tough to tell. I took this for a friend shortly after I got it and it wasn't intended to measure the plate height.

I'll see if they can take a photo for me because I see what everyone is getting at and this really helps.. it helps me with a discussion point for them.

I didn’t even notice it was a counter engine. Not sure it matters . But check the level of the transducer mounting, it looks like it’s hanging down too far but could just be the angle of the picture. That can cause a lot of spray as well if not just right.
The counter engine might actually be a plus with one person at the wheel on port side.
Old 06-02-2021, 07:49 AM
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Originally Posted by Tangled Up View Post
Raise the motor and add some lenco trim tabs. The tabs will help big time. You should not overheat by raising the motor. The water pickup should be in the nose cone of the lower unit.
The water pick up is in the nosecone only on certain high-performance motors. For the most part, it is on the side of the lower unit just above the bullet of the gear case. However, motors can pick up cooling water just fine even when those openings for the water are above the waterline because the bullet of the lower unit tends to route a sheet of water down the side where those pick ups are.
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Old 06-02-2021, 07:53 AM
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Not to be pedantic but your transducer is mounted on the wrong side for a counter rotating engine. Might not have any effect at all but another thing I've learned in all my research.
Old 06-02-2021, 07:54 AM
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Dacman, good call on the counter rotation.

OP, did you realize this? Was the engine one they had in inventory? The skeg is almost touching the ground. Seems to be the wrong shaft length for that boat but not sure. The engine computer will not allow overheat damage, total BS on dealer.

What is the model number of the engine?
Old 06-02-2021, 07:55 AM
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On a separate note, I do recognize from the photo that it is quite possible this is a 25 inch motor on a 20 inch transom. Without looking at my own prop, I cannot address right hand versus left hand, but it seems that many here think itís a left-hand motor. I assume this was either a used boat, or a boat where the dealer hangs the motor; actually, you said you were breaking it in so it must be a new boat, but it is entirely possible, particularly if itís a 25 inch motor on a 20 inch transom, that you just have entirely the wrong specifications motor on that boat. Looking at all the threads about the difficulty of dealers obtaining motors, particularly if you confirm itís a 25 inch motor, your dealer may have just hung what he could find on the boat rather than the correct motor.
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Old 06-02-2021, 08:08 AM
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The transom is 25".
Old 06-02-2021, 10:34 AM
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Originally Posted by Gary999 View Post
Dacman, good call on the counter rotation.

OP, did you realize this? Was the engine one they had in inventory? The skeg is almost touching the ground. Seems to be the wrong shaft length for that boat but not sure. The engine computer will not allow overheat damage, total BS on dealer.

What is the model number of the engine?
SURE looks like a 25" motor on a 20" transom!
AND counter rotating seems suspicious, as in the only motor they could find. ???

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