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Author Topic:   TRIM TABS On Montauk
dchapp posted 11-26-2001 04:11 PM ET (US)   Profile for dchapp   Send Email to dchapp  
I am considering putting trim tabs on 85 Montauk, boat has new Yamaha 4s 100, hoping the tabs can help with the list to port as well as the porpoising. Any thoughts?
JFM posted 11-26-2001 04:58 PM ET (US)     Profile for JFM  Send Email to JFM     
Are your batteries and fuel in the stern? The motor is a lot of weight back there by itself. I would try to move as much weight forward as possible. Regards, Jay
dchapp posted 11-26-2001 05:05 PM ET (US)     Profile for dchapp  Send Email to dchapp     
Battery has been relocated to console, fuel is under the seat.
larimore posted 11-26-2001 10:22 PM ET (US)     Profile for larimore  Send Email to larimore     
I put Bennett tabs on my 22 outrage and it made a major improvement. No problems with the tabs after 6 or more years. A lot of weight in the rear will cause the problems you spoke of... The tabs will eliminate those problems. I think the tabs were some of the best money I spent on the boat.
Barnett Childress posted 11-27-2001 07:32 AM ET (US)     Profile for Barnett Childress  Send Email to Barnett Childress     
What tabs are you thinking of installing? I've been looking at Bennett's Tournament series 810 tabs. Talked to them earlier and they are usable on a Montauk. If you install tabs I'd love to know how it turns out. I'm pretty sure I'll be installing the Bennett's next spring. My boat is stored for winter.
Whalerdan posted 11-27-2001 08:17 AM ET (US)     Profile for Whalerdan  Send Email to Whalerdan     
Just a question here. Can you trim out the porpoising? I know it's not the most efficient way to run but I was just wondering.
kingfish posted 11-27-2001 09:10 AM ET (US)     Profile for kingfish  Send Email to kingfish     
Lots of earlier references to trim tabs in the forum (although not for Montauk specifically)- wouldn't hurt to search and read what has been discussed to date.

Trim tabs will control porpoising, but so will Doel-fins. They won't do anything for side-to-side trim, but I have never heard of a Montauk that couldn't get porpoising under control with Doel-fins and correct motor trim.

If you do decide on trim tabs, take a look at Lenco tabs, as they are all electric and you don't have to mess with hydraulics and a place to put the hydraulic pump on a small center console boat.

Bigshot posted 11-27-2001 09:43 AM ET (US)     Profile for Bigshot  Send Email to Bigshot     
I heard those spring trim thingys work good on Montauks. Guess I am not getting a 100 Yamaha.
Whalerdan posted 11-28-2001 07:55 AM ET (US)     Profile for Whalerdan  Send Email to Whalerdan     
I agree. Looks like a good engine but it's a monster. Seems way big for a montauk.
dchapp posted 11-28-2001 08:25 AM ET (US)     Profile for dchapp  Send Email to dchapp     
Engine works great,but with the extra weight I am afraid I am robbing the engine of its ability by having to keep it trimmed down to far to help eliminate the porpoise problem. I would hope the tabs would help.
Bigshot posted 11-28-2001 10:00 AM ET (US)     Profile for Bigshot  Send Email to Bigshot     
If they help then you are not getting the full potential either due to drag. Try a doelfin first.
llewellyn posted 12-08-2001 03:10 PM ET (US)     Profile for llewellyn  Send Email to llewellyn     
Dchapp, Recommend reading the Montaukmax query & responses above if you have any flexibilty regarding mounting engine to transom. The Yamaha 100 is only about 50lbs more than the Merc 90(2 stroke). I believe
relative location of anti-cavitation plate to hull bottom is critical.Lew
andygere posted 12-09-2001 08:59 PM ET (US)     Profile for andygere  Send Email to andygere     
I have a stern heavy Montauk: 85 hp Johnson, 15 hp kicker on a bracket and stern mounted dual batteries. I have a Whale Tail (Aluminum anti-cav plate extension) similar to a Doel Fin. It acts like a big center mounted trim tab, and I can eliminate porposing easily with light and heavy loads just by adjusting motor trim. Trim tabs on a 17' boat are overkill.
Vic posted 12-14-2001 02:11 PM ET (US)     Profile for Vic  Send Email to Vic     

Trim tabs would definitely be a benefit to your boat. I know a boater who recently put tabs on a 17 SeaOx, and it made all the difference in the world in ride quality, seakeeping ablility, etc.

Generally, outboard engines run most efficiently with a certain amount of upward trim. (the whitewater dragging behind the engine dissappears, which indicates less drag)

However, this may cause your boat to porpoise. having the tabs will allow you to most efficiently trim your engine, as well as adjust the running attitude of your boat to compensate for any number of things- Sea state, porpoising, uneven athwartship passenger load, moving cargo load, etc. You can even make quick adjustments as you approach a boat wake, or when a passenger moves around. With tabs, you are always in control of the running attitude of the boat.

In addition, a boat trip with a "side-sea" could cause you to get covered in spray. With the trim tabs, just trim the leeward side downward a bit, and the spray will often pass behind you.

I have tried the doelfin-style add-ons, but they typically create a good bit of drag, and they requuire holes to be drilled in the cavitation plate. I wouldn't suggest doing that to your new motor. Even if this add-on does give you some counteraction to your porpoising problem, it still will not do away completely with the problem, and certainly cannot give you all of the benefits of trim tabs.

My 2 cents worth


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