missing starboard trim tab

[geoffm70]

I have a feeling this going to be really bad news. this re a '94 3200scr.

We had some nasty winds in Nanaimo yesterday, while trying to 360 in place, I had to use a fair amount of throttle (2300rpm) on my starboard engine in reverse. I don't suppose if my tab was down slightly, this could break the tab off? The ram is still there.

[mmwjr]

High rpm against a strong wind doesn’t mean that the boat moved backwards at a high speed so hard to answer. Most likely the tab was nearing failure anyway. Is the hinge still screwed to the hull?

[geoffm70]

I had to use about 2500 ram to counter the wind while trying to pivot, was hoping the prop wash force could maybe take it out?

[geoffm70]

The screw plate is gone, but the ram is still there.

[shrew]

Have you been using zincs on the trim tabs?

Was the hing for the tab still attached to the hull, or did the entire hinge rip out of the hull as well.

If the hinge is still in place, then I suspect galvanic corrosion of the aluminum weakened the tab.

if the entire hinge ripped out of the hull, then check to see if the transom is soft.

[geoffm70]

The screws ripped out. Tomorrow she comes out. Fingers and toes crossed my transom is okay!

[geoffm70]

Oh, and yes I have been using zincs on the plates.

[mmwjr]

Since the screws pulled out I would check for the integrity of that area of the transom as shrew mentioned.

[shrew]

Backing with the tab down won't typically tear the tab out. You likely have water intrusion which rotted the transom core.

Good luck

[geoffm70]

my transom is solid, screws rusted and both broke and pulled out. did both the hammer test and a moisture meter. off to stand next to the surveyor, insurance is requiring, been 5 years since her last when I bought her. time is just flying bye now at 56!

[mmwjr]

Originally Posted by geoffm70

my transom is solid, screws rusted and both broke and pulled out. did both the hammer test and a moisture meter. off to stand next to the surveyor, insurance is requiring, been 5 years since her last when I bought her. time is just flying bye now at 56!

Based on the picture the hinge base plate is still attached although all the fasteners are missing which I’m assuming you removed. While the trim cylinder is there the end is broken off. Not sure I would make an insurance claim for this. The cost of a new set of tabs vs a rate increase for several years, your decision.

[shrew]

I don't see the screw heads, I think the pic is misleading. You might have a galvanic corrosion issue. The support for the (swimplatform) is corroded. The screws all corroded and the ram for the trim tabs sheared weird too.

[yahoo82]

A little hard to see exactly what’s is in the pic. Is that rectangle the metal trim tab baseplate or is it the unpainted transom? I noticed the bottom paint is covering the swim platform supports. Some bottom paints cause galvanic corrosion due to their copper content. If your tabs were painted over this could be the issue. Generally speaking the ablative copper based bottom paint should be kept away from stainless and aluminum.

[geoffm70]

She's still in the yard, tab's been replaced. Servicing and repainting legs. My marina and the aluminum boat next to me has some electricity in the water I think. The starboard side zincs were mostly used where the portside, almost new after 7 months. The rust you see was the mounting plate, screw heads were all gone with the tab. I will replace the zincs on the swimgrid pole, along with the rest. Don't see any rust on the swimgrid mount or screws? New plate picture attached.

Insurance surveyor (5yr survey) spent at least 30min on the transom and when it was over, increased the value of 'Therapy' from cad 55k to cad 65k!