Best Size Trim Plane

[tank1949]

I posted this request under the Mercruiser I/O section, but some viewers in this forum may be able to provide a better response.

I found out the other day that my trim system is woefully too small. I have hyd. 12x9 tabs on a 29 ft Proline. Bennett recommends 18x12 with down fins on the side due to the limited stern area available to add larger tabs. Bennett doesn't make trim planes with larger than 12" chords. However, for those of us who have heavy dual I/Os with limited trim span areas, perhaps a 14" chord might be even better. I can get larger ones (18x14) made at local fab shop, but Bennetts have always been the chosen trim makers. Any suggestions???????.

 

[Tabman]

Re: Best Size Trim Plane

Do you have a photo of the boat's transom you can post?

 

[tank1949]

Re: Best Size Trim Plane

 

[NYBo]

Re: Best Size Trim Plane

Do you have a photo of the boat's transom you can post?

Hey, Tom, welcome back!!
(Sorry for going off topic.:redface

 

[Tabman]

Re: Best Size Trim Plane

Those are TrimMaster Brand Trim Tabs (been out of business for quite a while now).

You could try adding 3" Drop Fin 12 x 12 Tabs.

 

[tank1949]

Re: Best Size Trim Plane

I am definately going with larger tab. I don't know if an 18" x 14" with DF would do any better than your 18x12DF. The 18 would be max span. I could extend chord to 14" . MJ has been very helpful and recommended 18x12df. Regardless or which size, I may have to use existing actuators because of the transome area being crowded with dive platform support beam. Existing actuators, centered to both piviot points is 11" extended. I suspet Proline used cheapest and what would fit. However, the current tabs perform poorly, but I am plagued with room constraints. I don't mind spending money to get performance but I don't want to spend a pile of it and not be satisfied. I have already sunk a bunch into this barge. Yiou don't happen to know the height of the 18x12df hinge backing plate? My existing ones are 2".

 

[Tabman]

Re: Best Size Trim Plane

I don't have that info at home but will get it for you Friday Morning.

Your hinge can be much closer to the hull bottom with the Bennett Hinge Plates. Since they are interlocking spray will not come out of the joints. It can be right at the bottom 0f the transom and will be a bit more efficient.

 

[tank1949]

Re: Best Size Trim Plane

I don't have that info at home but will get it for you Friday Morning.

Your hinge can be much closer to the hull bottom with the Bennett Hinge Plates. Since they are interlocking spray will not come out of the joints. It can be right at the bottom 0f the transom and will be a bit more efficient.

tabman thx for you and MJ responding. The best that I can tell is that boat hull thickness in 1/2 " . So, I'd have to drill at least 1/2" from flat side of hull to install trim planes. What is backing plate height and is is pre-drilled on 18x12df? My current tabs are 2". MJ indicated that these tabs were installed too high. They are about 3/4" away from flat of hull. I suspect previous installer may have tried to avoid drilling into flat of hull?

I examined your actuators bot std and short models, which I am assuming both will provided adaquate force and length (extended) to operate 18x12 plane correctly. It seems that the std length would provide greater strength, but as I described above, my swim platform's spar might be in the way of the top part of the actuator. You may be able to examine photos to see. Current actuators are 11" fully extended (in photo) from center pivot point to center pivot point. Does Bennett provide installation instructions, if any??????? I have lots of tools. If not, know of a good U-tube???? I'll search too. Thx!!!

 

[Tabman]

Re: Best Size Trim Plane

Tank,

Our mounting plates are 2-5/8" tall and the mounting holes are 1" from the hull bottom.

Our standard actuators are 13-3/4" overall from top to bottom when retracted and have a standard stroke of 2-1/2".


We also make them 11-3/4, 12-3/4 and 10-3/4
and they are strong enough for a 42 x 12 or 54 x 9 Trim Tab with a single actuator.

Here is a link to installation instructions http://www.bennetttrimtabs.com/pdf/instIcon/trimtab_installation.pdf

Let me know if you need any other info.

Tom
Bennett Marine

 

[tank1949]

Re: Best Size Trim Plane

Tabman. Thx I will cut cardboard today and examine my options of what wil and will not fit.

 

[tank1949]

Re: Best Size Trim Plane

Tabman,


You web site states coat ss screws holding backing plates with epoxy. Will 5200 work as well? I have a little Get Rot left. If that will do?

 

[Tabman]

Re: Best Size Trim Plane

I have used 5200 and 4200 with success. I likely would not use Get Rot, as it is designed to soak in, not seal.