Trim Tabs

Corrosion, Paint, Through Hulls, etc.
louism58
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Trim Tabs

Postby louism58 » Tue Dec 15, 2020 4:01 pm

Well with the boat out of the water I got a good look at the tabs.

They are in good shape for a 1973 boat but after measuring it is clear why they do not level the boat off the way I expected.

I have a 32' boat with 24x 9" tabs.

Looking at all the guides at a minimum these should be 24 x 12" actually 30 x12 would be better.

I think I will pull the old ones off and put new tabs on to get to 24 x 12

I was measuring the 9" from the hinge back so only the part that moves I assume that is the correct way to measure.

I went on line to see about ordering set and but it seems every other boat in the country needed a set of 24x12 tabs for Christmas everyone was out of stock!

I also an pulled all 5 batteries and so far 3 were bad not charging so will be replacing them for the new season as well.

Louis

Fastjeff
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Re: Trim Tabs

Postby Fastjeff » Tue Dec 15, 2020 5:14 pm

..."...pulled all 5 batteries and so far 3 were bad not charging so will be replacing them for the new season as well."

Oh, the joys of yachting!

Smart move to go with larger tabs vs. shoving them down further (as I did with my dink boat hanging on the swim platform). Lost at least 2 mph cruising speed by shoving the port tab down another inch or so with a spacer.

Jeff
"We live at the bottom of an ocean of air, not at the top." General Marvage Slatington

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bcassedy
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Re: Trim Tabs

Postby bcassedy » Thu Dec 17, 2020 7:35 am

Jeff
Just wondering...
If getting new 12x24 tabs gets better results because the amount of tab extending out from the back of the boat has been increased,
wouldn't adding additional plating to an existing trim tab accomplish the same thing?
- if you're using the same cylinders to mount new tabs, the new tab mount points would have to be located at the same position as the old tabs,
- you >> should << then have the same 'new area' behind those mount points (as would be the case in an owner mounted tab extension).
--> I would think such a new tab/original cylinder mount point setup would get the same increase in drag as you experienced with the extension addition to the existing tab.

Or, would an owner need to buy a complete tab system, including new longer cylinders that allow for a further aft placed mount point on the new tab? There I could see a similar down angle of the new tabs as the old tabs but with a greater surface area for the water to push against without increasing drag as you experienced.

Bill
Last edited by bcassedy on Fri Dec 18, 2020 8:01 am, edited 2 times in total.
Bill & Sharon Cassedy
"Sunset Seeker"
'88 32' Sedan Bridge
Located in Aurora, In.
Twin 318cu in Chrysler
1.5:1 Velvet drive trannies
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Fastjeff
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Re: Trim Tabs

Postby Fastjeff » Fri Dec 18, 2020 6:56 am

All good but unanswerable questions.

Thanks to that heavy dink boat hanging off the swim platform, I could not get the bow down, even with full down tabs. I added a shim (about an inch thick as I recall) between the ram and the tab. It got the bow down, but I lost 2 mph in cruising speed. You'd think that the use of trim tabs in ALL cases would increase drag and slow the boat, but they of course do not.

Would a longer or wider tab have worked better? Quite possibly, but you never know without testing.

Sorry but I can't be of more assistance.

Jeff
"We live at the bottom of an ocean of air, not at the top." General Marvage Slatington