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Old 10-20-2015, 10:11 AM   #21
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And Rich, good to see you on here again!!!!
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Old 10-20-2015, 10:31 AM   #22
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What year is your hull? It might fit in my lift. If you had the replacement drop fin trim planes complete, the swap out would not take but a few minutes.
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Old 10-22-2015, 06:35 PM   #23
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Thanks for the offer Rich. I may take you up on that, maybe later this winter. I have a list of other projects I want to do on my boat first. My boat is an '06, same hull as yours.

FYI, I ran my boat last night and noted the numbers:

WOT (3800 rpm) = 23 knots
3200 rpm = 18 knots
3000 rpm = 17 knots

Not heavily loaded: 2 people, tanks were half full.
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Old 10-23-2015, 05:41 AM   #24
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Thanks for the info. With full tanks and hardtop AC, radar, generator, full fuel and water I am guessing I am at least a 1,000 pounds heavier than the condition you were running. I will be interested to see how I do once I burn through half m fuel. I'll bet I can regain the 2-3 MPH you have on me at WOT. One ting I want to do is get my digital tach on the engine at WOT to see if I am getting the rated 3800. I think I am a bit below that now. Once I have determined that and am sure of the engine-mounted fuel filter, I am going to have the prop tuned when I haul the boat for a touch up bottom and running gear paint job - probably next year.
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Old 10-25-2015, 10:25 AM   #25
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Well then...there is the difference. I did no know that engine was rated at 3800rpm. That explains it. All your extra power is in that upper range. The 4LHA-STP is rated at 3300rpm.
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Old 10-25-2015, 02:42 PM   #26
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Quote:
Originally Posted by Keysdisease View Post
The "drop fins" capture water that would normally slip out the side increasing the efficiency of the tabs by about 25-30%. The edges of the tabs must be parallel with the keel to use these.

Bennett doesn't weld because it changes the properties of the stainless and could increase the rate of corrosion. There are a few manufacturers that insist on welding on tabs and in those cases Bennett does weld but then passivates the tabs.

Most Bennett Tabs can easily be removed for the "drop fin" mod by disconnecting the actuator and loosening the hinge screws into the transom. At some point the tabs will clear the locking tab and just slide out the side without removing the hinge entirely.

A little known fact is that on many Bennett tabs sold to Mainship the Actuators were restricted in their travel. Mainship did this to avoid bow steering and along with the minimum sized tabs on the Pilots this restricted the performance of the tabs. A standard Bennett Actuator travels 2.5". The modified Actuators travel 1.75". If you have a modified actuator there will be a label on the bottom of the lower hinge (where it attaches to the tab.)

Another easy fix for a little more performance is an actuator spacer. Bennet will give these to you for free for the asking. They are triangular and the same footprint as the upper hinge where it attaches to the hull. It is notched to fit around the brass nipple that carries the fluid and is easy to install, even in the water for most boats. You just back off the 3 screws in the transom, slip the spacer between the actuator and the hull, goop it all up, and re tighten the screws. Gives .5" additional travel down but does away with the - angle Bennett recommends.

Dougcole, Mainship used 12" x 48" tabs with dual actuators and 1' upfins for the entire run of 400's. You might check if you have restricted stroke actuators which would be the best way for you to improve performance.

Most of the above are "fixes." There's nothing better than a bigger tab, I had 12" x 42" on my olde '78 MSI and they were the difference between planing or not. There are ways to install bigger tabs on most boats, and the single actuator is standard up to 12" x 42" tabs.

Good luck,

Thanks so much for this great info on the tabs. Can you give me a little more info on what the restricted stroke actuator label will look like if present? Will it be some sort of tag, or embossed on the hinge?
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Old 10-26-2015, 05:27 PM   #27
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It will be a white label on the bottom of the lower hinge, the part that's in contact with the tab. You can also measure travel, 2-1/2" is standard for the ram, travel will be more at the training edge of the tab because the actuator attaches at 8-5/8" from the transom. You could also call Bennett and ask them to look up the 12 x 48 transom mount kit they sold Luhrs. 954 427-1400, ask for Thomas and tell him I sent you.

If you are on the hard its pretty simple to return to standard travel, the cylinder unscrews and the internal "stops" where the modification is made is easy to modify back to standard.

You don't have to disturb the plumbing at all.



Quote:
Originally Posted by Dougcole View Post
Thanks so much for this great info on the tabs. Can you give me a little more info on what the restricted stroke actuator label will look like if present? Will it be some sort of tag, or embossed on the hinge?
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Old 04-14-2016, 04:20 PM   #28
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I just finished installing the Bennett drop fin kit to the tabs on my Mainship Pilot 34. Like I said earlier these tabs are recessed into the hull and don't extend beyond the transom.


But they fit up fine. I screwed them in place with #10-32 x 1/2" SS screws and lock nuts. I couldn't reach the forward most hole to fit a nut on so I just used the aft three holes which seems to hold fine.


The only problem, which I anticipated was drilling the SS trim tab. It is about 1/8" thick and I went through four 3/16" bits to drill 12 holes.


The boat gets launched in 2-3 weeks and I will report then on any performance improvement.


David
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Old 09-28-2019, 12:44 AM   #29
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Quote:
Originally Posted by djmarchand View Post
I just finished installing the Bennett drop fin kit to the tabs on my Mainship Pilot 34. Like I said earlier these tabs are recessed into the hull and don't extend beyond the transom.


But they fit up fine. I screwed them in place with #10-32 x 1/2" SS screws and lock nuts. I couldn't reach the forward most hole to fit a nut on so I just used the aft three holes which seems to hold fine.


The only problem, which I anticipated was drilling the SS trim tab. It is about 1/8" thick and I went through four 3/16" bits to drill 12 holes.


The boat gets launched in 2-3 weeks and I will report then on any performance improvement.


David
David,

I know you sold your Pilot 34, but do you remember the difference in performance you experienced after installing the Bennett drop fin kit? My boat has bottom-mounted tabs at the extreme outboard edges of the transom. Due to their location and deadrise angle, a lot of the flow under the tabs is lost out the sides. There are actually horizontal rooster tails from the tabs when fully deployed. This is lost lift that I'd like to re-capture without extensive mods.

Thanks
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