Trim tabs

Gypsymagic · Sep 7, 2024

Any comments on the use or need of trim tabs on a GB 42C?

Trying to decide if I should remove mine as they have not worked since I bought the boat. I’m a single Cat 3208 375 hp and even at WO I can achieve not more the 12 knots.

Papas · Sep 7, 2024

On my 46 w/ twins, the tabs work just fine, but that doesn't mean they are effective. At WOT, trimming bow down may gain an additional 1/4 - 1/2 knot, but going from 3gph / side at normal cruise to 16+gph/side means they are almost always left in a neutral position (as normal cruise vs. WOT is all of about a 2 knot difference). I've absolutely considered removing them so I have one less system to have to maintain. IMHO, you don't need TT's on a semi-displacement boat like the GB (unless you have twin 475 beasts).

JohnP · Sep 7, 2024

I have removed mine. Only rarely used them. They were hard for me to keep clean, guess I never got the primer right to keep the paint on. Only once reached 14 knots. Light on fuel, water, and stores, not the way I like it. Happy to cruise- 7 to 8 knots, no need to plane. At 14 the fuel use use beyond me and the noise level was not what I wanted. If someone wants a faster trawler this boat in not the one. Keel is long and deep and the hull is heavy. Probably the same with GB boats.

Pat T · Sep 23, 2024

Gypsymagic said:
Any comments on the use or need of trim tabs on a GB 42C?

Trying to decide if I should remove mine as they have not worked since I bought the boat. I’m a single Cat 3208 375 hp and even at WO I can achieve not more the 12 knots.

I have twin 3208TA's at 435HP each. Seems the trim tabs only come into effect at about 2100 rpm if I recall. At that speed I might gain 1/4 knot. At 2400 I might get 3/4 knot. I usually (90% of the time) cruise at 1400 and average 9 kts. No TT necessary. Above 2400 rpm's, who knows, I might gain 1 knot. It's rare that I run above 2400 rpm so I can't comment.

mike r smith · Sep 24, 2024

Gypsymagic said:
Any comments on the use or need of trim tabs on a GB 42C?

Trying to decide if I should remove mine as they have not worked since I bought the boat. I’m a single Cat 3208 375 hp and even at WO I can achieve not more the 12 knots.

My old Fairways Trawler 38. 16.6 tons with a long deep keel. Twin 212 BHP Ford Sabres. The hydraulics were removed, and the tabs were fixed down. Would make 18kn and cruise at 12 to 14. I considered there was little penalty at 7 kn or 9 kn long range cruising.

Bob Jack · Sep 24, 2024

We have twin cat 3116 ta 300 hp each. While I have not noticed any increase in fuel consumption I can say that by using the trim tabs at any speed above 8 kts the visibility is greatly improved by lowering the bow with the trim tabs.

hmason · Sep 24, 2024

My GB 46 had trim tabs. At trawler speeds they did nothing. I never bothered to use them.

NightCrawler · Sep 25, 2024

Frankly, I called them 'razor sharp ironing boards." We used the swim deck a lot to enjoy the water off the boat. Can't tell you how many times someone's shins were skinned up getting back in. Took them off and never missed them a bit. Easily done. Just be sure to thoroughly dry the old holes before filling them in.

rslifkin · Sep 25, 2024

NightCrawler said:
Frankly, I called them 'razor sharp ironing boards." We used the swim deck a lot to enjoy the water off the boat. Can't tell you how many times someone's shins were skinned up getting back in. Took them off and never missed them a bit. Easily done. Just be sure to thoroughly dry the old holes before filling them in.

Interesting that they presented an issue boarding from the water. My boat has 12" chord tabs and a 20" deep swim platform (so the edges of the tabs are 8" in from the edge of the platform). We've never had an issue with hitting them while getting onto and climbing the ladder out of the water.

Trim tabs

Gypsymagic

Veteran Member

Papas

Veteran Member

JohnP

Guru

Pat T

Senior Member

mike r smith

Member

Bob Jack

Member

hmason

Guru

NightCrawler

Senior Member

rslifkin

Guru

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