Trim Tabs location vs Hull Strakes / Chines

Hey all,

 

Just after some advice regarding location of trim tabs.

 

Ideally, it's best to mount the tabs as far from the engine as possible to give the most L/R lean control.

But the outer strakes on my hull extend all the way to the transom, and is right in the middle of what I'd reckon to be  the best location for the tabs.

I'd reckon this must have some sort of effect on the flow under the tabs, possibly affecting performance ?

 

The tabs are 12" wide, so I've put some tape in 4 different locations to show you what I'm on about - see below.

 

Option 1 is probably too far out, making the tabs vulnerable to damage when out of the water.

Option 2. Without any strakes, this would be the best spot, but on my hull there'd be a strake right in the guts of each tabs.

Option 3 is probably the best compromise.

Option 4 is nice & clear, but way inside where you'd normally want them to be.

 

If anyone's had some experience installing the tabs in a case like mine it'd be great to get some feedback / advice.

 

Thanks,

 

Dizz.

 

 

 

 


snappermiles's picture

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option 2

Mon, 2011-10-03 14:37

is where i put mine on my boat and i have a chime in the same spot,  they work great!

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alfred's picture

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Where is your tranny? I'd

Mon, 2011-10-03 14:45

Where is your tranny?

 

I'd choose Option 1, as far out as you can.

 

 

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sorry to hyjack thread alfred

Mon, 2011-10-03 17:31

sorry to hyjack thread 

alfred your tranny set up do you ever adjust it or is it kept in one positon

ive seen a feew adjustable  brackets like yours and wonder why? and whats the benifits?

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alfred's picture

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It's up only when I trailer

Mon, 2011-10-03 18:31

It's up only when I trailer or intend to launch at very shallow ramps.

Dizzy's picture

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Thanks for the quick

Mon, 2011-10-03 15:00

Thanks for the quick replies.

 

The new Tranny (transom-mount) is yet to be fitted - figured I'd get the tabs in the best spot and work around them.

Brucesta's picture

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option 1 or 2, further out

Mon, 2011-10-03 15:06

option 1 or 2, further out the better they will be and just make sure you put the transducer in clear water not turbulant water.

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Sure, but best to check how

Mon, 2011-10-03 15:37

Sure, but best to check how much of the transom is getting wet at the speeds you intend to use it!

#2 looks ok, the interplay between the trim tabs and the tranny is a bit of a worry though.

What transducers? Transom mount or wetbox?

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Dizzy's picture

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Transducer is a 600W Transom

Mon, 2011-10-03 15:58

Transducer is a 600W Transom mount Simrad / Lowrance.

 

You're right about checking water under the transom at speed.

 

To add confusion, it seems the yanks on the forum below all mount theirs in Option 4

 

http://www.bdoutdoors.com/forums/boat-electronics/55200-trim-tab-location-transducer.html

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4 is always going to work,

Mon, 2011-10-03 16:25

4 is always going to work, its just the shortest lever and may get in the way of the transducer.

I really can't help but think that glass boats ought to come with wetboxes.

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Lamby's picture

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Agreed, I had issues with the

Mon, 2011-10-03 19:12

Agreed, I had issues with the 600w getting clear water due to the trim tabs it became farcical trying to place the bastard therefore no consideration was given to transom mount for the 1kw. 

alfred's picture

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I can almost guarantee that

Mon, 2011-10-03 16:25

I can almost guarantee that unless the boat is very overpowered, all horizontal lines will be wet when travelling in a straight line

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I've seen boats with the last

Mon, 2011-10-03 17:07

I've seen boats with the last 1' of transom clear, thats the only thing that makes me pick #2 over #1.

Now that I think about it, maybe even if a little bit of #1 was in the water, the extra amount over leverage would compensate, as well as leave more clean water for the tranny?

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Dizzy's picture

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The old transducer was near

Mon, 2011-10-03 15:24

The old transducer was near where alfred's got his, but unfortunately on my boat it was crap over 10-12 knots. (Airmar P58)

Hopefully new Simrad transducer will be better, but I'll experiment with position a bit before drilling holes.

alfred's picture

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Mine is right behind the

Mon, 2011-10-03 16:27

Mine is right behind the stake, cleanest hit at that point.

grayzeee's picture

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as mentioned , might be an

Mon, 2011-10-03 16:10

as mentioned , might be an idea to work around the transducer position , rather have that working effectively first , then go from there.

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alfred's picture

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Oh, get QLs and forget the

Mon, 2011-10-03 16:28

Oh, get QLs and forget the tab units.

Dizzy's picture

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I'd have done QL's too, but

Mon, 2011-10-03 21:55

I'd have done QL's too, but they were going to be a bitch to fit to my boat

 

The position of the comparatively big 32mm hole is only a small distance up from the bottom of the hull, which is under the floor on my rig and almost impossible to achieve without major access headaches / mods.

 

Have seen a few un-installed units up for sale after buyers realised they were up against the same issues.

 

Have a look at the installation manual and you'll see what I mean.

 

http://www.great-water.com/pdf/QL_Manuals/Trim_Sys_%20install.pdf

smash's picture

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"Have seen a few un-installed

Mon, 2011-10-03 22:25

"Have seen a few un-installed units up for sale after buyers realised they were up against the same issues."

whereabouts-Ive been looking for a set?

Dizzy's picture

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Was months ago while I was

Mon, 2011-10-03 23:26

Was months ago while I was googling everything before I even discoverd the Minn-Kotas.

Think it was Ausfish or Fishnet forum, plus a set on ebay (which may have been one of the same sets from a forum).

 

The  asking price was only marginally lower than new - though they'd have had to drop the price to sell, so maybe they went cheap in the end.

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Read the Installation manual

Mon, 2011-10-03 16:48

My Lencos came with quite clear guidelines about distance from Chine and strakes, so option 2 I think.

Dont know what brand your tabs are but see page 5 or 6 for what Lenco recommend:

http://www.lencomarine.com/Resources/TT%20manual_Feb-1-10%20Final.pdf

alfred's picture

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I have the Lencos as well. 

Mon, 2011-10-03 18:37

I have the Lencos as well.

 

Dizzy's picture

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Thanks Mate, That's a good

Mon, 2011-10-03 22:04

Thanks Mate,

 

That's a good enough guide for me - I'll do it per that manual.

 

Mine are the Minn Kota tabs (moulded composite) - they've got a bulge / domed in the middle on the underside, but shouldn't make too much difference.

 

Thumbs up !

 

Dizz.

marble's picture

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Our tabs have a strake

Mon, 2011-10-03 17:38

Our tabs have a strake finishing about 150mm in front of them and directly in the centre. Seem to work fine so I wouldnt worry about the strakes. Get the transducer working well first I reckon and then worry about the tabs.

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nico's picture

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  Dizz 2 or 3 would be

Tue, 2011-10-04 07:02

 

 Dizz 2 or 3 would be fine,personal choice and like the boys said keep in mind of all the other fittings screwed to the trany. 4 is  for a high performance hull when there is less surface area of a hull in the water. 1 would not run full contact at all times with the water .

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Dizzy's picture

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Thanks Nico :) Are you saying

Wed, 2011-10-05 21:40

Thanks Nico :)

 But are you saying my Chivers ain't a high performance hull ???   hehe.

solly's picture

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no 3

Wed, 2011-10-05 20:04

 I have minn kota tabs on mine,they are on the inside my boarding ladder.I run athrough hull tranny and I still get bottem at 35 knots so this might be abetter option for you also no problems at shallow ramps.The minn kotas are very sensative above 20 knots so i find it better to set myself up before upping the revs.Dont touch them at speed as they will steer you if you know what I mean. Apart from that they are very good.(I will try and send a pic later)

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Dizzy's picture

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Thanks Solly, Would be good

Wed, 2011-10-05 23:28

Thanks Solly,

 

Would be good to see a pic or 2 of your setup.

What size tabs & actuators have you got ?

 

Mine are the 9"x12"W tabs with SHORT stroke actuators. 

Increased sensitivity is one of the issues of mounting closer to the engine, as a slight adjustment will have more "lift" due to the decreased distance from the hull's V.

 

.