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Old 03-14-2018, 07:24 PM   #21
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The builder apparently believed that operational tabs were useful for the boat's operations. So, on first thought, get them operational and work with them. You might be pleasantly surprised. Nevertheless, if you're satisfied with the boat's operation, either forget about or remove them. ... Fortunately, my slow boat has no need for the complication.
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Old 03-14-2018, 07:59 PM   #22
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If the tabs are underwater at your normal cruise speed, I would guess that the turbulence they create is more of a hindrance than a help. The huge negative pressure area created above them is a braking force.
Removing them just might result in improved speed and economy!
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Old 03-14-2018, 09:01 PM   #23
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One final thought, you might post on the GB forum whether any one with your model boat has trim tabs and at what speeds and conditions they make a difference. Having someone on this forum tell you it doesn't make a difference on their (different manufacturers) boat, so it won't make a difference on yours, seems not very valid. I would be very surprised if someone on the GB forum hasn't got the answers you want.

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Old 03-14-2018, 09:11 PM   #24
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The GB was designed as a semi-displacement hull and then they installed engines insufficient to plane. Then, as sales fell, they put large engines in the same hull and used trim tabs and strakes on the bow so they could "plane." A modern (10 year-old) GB 42 Europa will do about 25 knots but its wake is only unimpressive to a tsunami survivor. If you can do the 17 knots you suggest, I would definitely fix them. My friend's Symbol does 18 knots and he uses his tabs then but he doesn't bother with them when cruising alonside me at 7.5 - 8 knots. I doubt if you would even notice them at 8 knots.
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Old 03-14-2018, 11:27 PM   #25
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I don't have trim tabs.

I have cruised extensively with a GB 36. My boat is 44. The 36 had no trouble keeping up and did so on less fuel burn than mine. No trim tabs. You be the judge.
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Old 03-23-2018, 10:13 AM   #26
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Adios Trim Tabs. After more conversation with the folks here where we are at Atlantic Yacht Basin in VA, we were more convinced to remove the tabs. They do excellent work, fiber glassing the holes and mounts, rather than just pumping 5200 into the transom. Got her a new bottom coat and we're good to go!!!

Oh, and many thanks for the thoughtful responses here on TF. Very much appreciate that.
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Old 03-23-2018, 10:29 AM   #27
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I have a new 45 ft. (SD/FD hull; Cruise 6-8K) boat arriving in a few weeks and it won't have tabs.
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Old 03-23-2018, 10:49 AM   #28
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Thank you for keeping us informed. She looks darn good. Good work!
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Old 03-23-2018, 11:36 AM   #29
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Quote:
Originally Posted by Xsbank View Post
Thank you for keeping us informed. She looks darn good. Good work!
+1 on both counts.
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Old 06-28-2018, 08:44 AM   #30
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Update on Tabs Removal

The trim tabs were removed in Chesapeake, VA. We're now in Toledo, OH. After running slow via the Erie Canal, and having some fun across Lake Erie, I'm convinced removing them was a good call. We've tracked fuel burn for the entire two years we've lived aboard Shangri-La, over 3,000nm. Removing the tabs made no difference at all. We do not notice any change in ride. (Keeping in mind, they were not functioning, just dragging along behind)

Thanks again to the group for thoughtful feedback.
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