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03-14-2018, 06:24 PM
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#21
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Master and Commander
City: Vallejo CA
Vessel Name: Carquinez Coot
Vessel Model: penultimate Seahorse Marine Coot hull #6
Join Date: Sep 2010
Posts: 12,530
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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. 
__________________
Kar-KEEN-ez Koot
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03-14-2018, 06:59 PM
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#22
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Guru
City: hawaii
Vessel Name: #31
Vessel Model: ex-Navy MUB 50 fish/cruise
Join Date: Aug 2013
Posts: 820
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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!
__________________
You can lead a horse to water,
But you can't make him ski...
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03-14-2018, 08:01 PM
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#23
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Guru
City: Fort Myers, FL... Summers in the Great Lakes
Vessel Name: Slow Hand
Vessel Model: Cherubini Independence 45
Join Date: Dec 2010
Posts: 12,043
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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.
Ted
__________________
Blog: mvslowhand.com
I'm tired of fast moves, I've got a slow groove, on my mind.....
I want to spend some time, Not come and go in a heated rush.....
"Slow Hand" by The Pointer Sisters
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03-14-2018, 08:11 PM
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#24
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Guru
City: Pender Harbour, BC
Vessel Name: Gwaii Haanas
Vessel Model: Custom Aluminum 52
Join Date: Sep 2013
Posts: 3,791
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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.
__________________
Don't believe everything that you think.
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03-14-2018, 10:27 PM
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#25
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TF Site Team
City: Saltspring Island
Vessel Name: Retreat
Vessel Model: C&L 44
Join Date: Nov 2007
Posts: 5,539
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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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Keith
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03-23-2018, 09:13 AM
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#26
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Senior Member
City: Beaufort, NC
Vessel Name: Shangri-La
Vessel Model: Grand Banks 42 Classic
Join Date: Feb 2016
Posts: 203
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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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03-23-2018, 09:29 AM
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#27
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Guru
City: San Diego
Vessel Model: Helmsman 4304
Join Date: May 2016
Posts: 1,954
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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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03-23-2018, 09:49 AM
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#28
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Guru
City: Pender Harbour, BC
Vessel Name: Gwaii Haanas
Vessel Model: Custom Aluminum 52
Join Date: Sep 2013
Posts: 3,791
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Thank you for keeping us informed. She looks darn good. Good work!
__________________
Don't believe everything that you think.
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03-23-2018, 10:36 AM
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#29
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Guru
City: Gig Harbor
Vessel Name: Kinship
Vessel Model: North Pacific 43
Join Date: May 2015
Posts: 9,045
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Quote:
Originally Posted by Xsbank
Thank you for keeping us informed. She looks darn good. Good work!
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+1 on both counts.
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06-28-2018, 07:44 AM
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#30
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Senior Member
City: Beaufort, NC
Vessel Name: Shangri-La
Vessel Model: Grand Banks 42 Classic
Join Date: Feb 2016
Posts: 203
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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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