Defever leaning to port...trim tab issue?

[CAcruiser]

Have a 68' defever w/displacement hull whose stern tends to lean to port when pushing 10 knots. I'm wondering if it could be a trim tab issue of some kind? Anyone have any experience with trim tabs? Other ideas?

[a64pilot]

If it's not caused by trim tabs, it certainly can be corrected by trim tabs

[Stumble]

Just to be sure, do you have counter rotating props?

[CAcruiser]

Good question. Port spins to the left, starboard spins to the right, so yes.

[goboatingnow]

On a 68 footer at 10 knots you'll not correct that short of huge tabs. Is she level at lower speeds. , or it's it progressive

Dave

[CAcruiser]

She's pretty level at lower speeds, however as we speed up the left rear dips down. I have some video showing water steadily flowing over the port side of the swim step while the other side is completely out of the water. We're trying to find photos of the last haul out to see if there are trim tabs. There is a 12v breaker that reads "trim tab" but that's all we've been able to find so far without getting in the water.

[Stumble]

A few more questions

1) are you positive that the props match? Both size and pitch
2) check the aft tail of the boat for trim tabs. If you have them check if they are in the same position
3) double check the props match
4) are you operating in shallow water?

If everything looks ok, then I can only think of one more thing, which is somewhat scary. You may have a warped boat that is creating dynamic instability. This is somewhat rare, and is a worst case issue. If you suspect this I would immediately fall defever about the problem.

[CAcruiser]

I'm pretty sure that the props match but we'll have to send a diver under to check on the pitch. We're still investigating to find out whether she has trim tabs and we may need the diver to check that as well. So far, we've only found a breaker but no indicators or controls.

We have on occasion operated in some shallow water in a few marinas but most of the time we are in very deep water. She's level when sitting and at low speeds so I'd be surprised if it the boat is warped as you've described--but then again I don't know much about it. I was hoping that it's a simple issue w/a trim tab. Yet, I'm learning that anything on this boat is not simple. :-)

[Stumble]

CaCruising,

One of the hallmarks of a warped boat is that they are level at the dock, fine at slow speeds, but as the boat speeds up the hull forces the boat over to one side. I don't know enough about this boat to begin to diagnose a problem like this, but I have seen it a few times. Typically it is either a bad hull from the factors, or caused by improper storage on the hard.

Good luck to you.

[GPSocal]

Kneel on your swimstep with a boat hook and run it down the transom to see if you have trim tabs. The trim tab wiring and hydraulic actuating pump should be mounted on the inside of the transom and visible from the engine room. If the port tab is down and the starboard tab level or up, the boat would heel at cruising speed. It may be just a wiring/power issue.

[HappyMdRSailor]

Have somebody operate the tab controls L&R up and down while you are at the pump... You should hear the same motor pitch for both sides... running... running at the limits.... and time to go from limit to limit should roughly be the same...

[Hoofsmit]

This is a bit bizarre, you have a 63 ft ocean cruiser and you are happy to take it to ten knots but you don't know if you have trim tabs !
they are fitted mainly with Bennett trim tabs , you really need to go to there site and figure ! They do auto trim system but you will have bow/ up switches at the helms even then
Sorry but I really cannot see how you can have this sort of craft and not know its systems, or you haven't hired a professional skip.
Do us all a favour and take some training because this is really basic motor cruising stuff.... Good luck, hope you get it sorted

[Pirate999]

I'd vote for a bad tab. Uneven Prop pitch would cause you to "pull" pretty hard at 10kts given the same rpm. Having run a couple of smaller Defevers a number of years ago, I'd doubt it's warped. It's possible.. But not probable.

It does sound like you have a bit of course work to do with your new boat.

[ranger58sb]

Originally Posted by CAcruiser

I'm pretty sure that the props match but we'll have to send a diver under to check on the pitch. We're still investigating to find out whether she has trim tabs and we may need the diver to check that as well. So far, we've only found a breaker but no indicators or controls.

Our trim tabs extend aft beyond the end of the hull, partly visible from the dock, and also discoverable with a boat hook. We have no indicators.

If you have trim tabs, you would likely have a pair of rocker switches at each helm station. One rocker works right tab, up, down... etc. They may or may not be marked as to function.

I understand working both rockers in opposite direction simultaneously will hose up the control system... maybe somebody has done that.

Or maybe one side isn't working for some other reason. Assuming tabs are the issue and Bennet is the brand, they'll help you fix it.

-Chris

[eyschulman]

Have you asked someone like a boat yard manager or master maintenance person to look into this? I would think a hands on approach by a knowledgeable person would be the direct and most fruitful approach. Even if this site comes up with the answer some one will have to confirm that.