[bclarke01]

I'm about to replace the portside trim tab on my 1998 Voyager 530 for the third time. Has anyone else had difficulties with their trim tabs?

A very basic question is:
Do you think the trim tabs make a noticable difference on the larger Carver models? What is the risk of going without?

The first couple of times I figured I had hit something. Now I'm not so sure. This time it appears the trim tab is bent.

Checking the Bennett Trim Tab website, they recommend 54" x 12" trim tabs for a boat over 50'. Carver installed 42" x 12". If one accepts that the load placed on a trim tab by a boat of a given size is fixed regardless of the trim tab size, the force applied on a smaller trim tab will be higher per square inch than on a larger tab. So if the tab were undersized, is it at greater risk of self-destruction than a larger one would be?

Thoughts anyone?

Thanks!

Bruce Clarke
S.F. Bay Area

[K1W1]

Hi,

Welcome to Yachtforums.

Force = Pressure x Area.

A larger tab will be subject to greater forces purely by it's overall surface area.

The loading on the operating mechansim will also be higher with a bigger tab.

I believe the website owner Carl has a background in Hydrodynamics so he may be able to expand on my minimalist answer with some numbers and equations.

[bclarke01]

Your math makes sense but my question is which variable is fixed? Force or pressure? I would think that Force was fixed for a given sized vessel traveling at a given speed. In this case pressure would reduce as area goes up.

But my exposure to proper hydrodynamics is now over 30 years old so on a good day is fuzzy. Hopefully Carl will reply and clear things up!

Thanks for the reply!

[RamSport47]

can I ask what happened to the tab? I've seen them "disappear" on several boats, and this happens when people reverse quickly. Carver has added stainless down angle limiters to aleviate this problem. If yours do not have this, contact your dealer to get them. they will bolt right in place without much problem. Keep in mind, this is not a recall or SB, but can be retrofitted at any time

[JohnnyBoy]

Bruce,
I own a 2004 57' Voyager...gotta tell ya...I don't feel a darn difference with tabs up/down... Everytime I take her out I try different settings...no difference. Not sure what size are on my 57' but regardless...I don't think they are doing a darn thing... Just my novice input.

[Wild Radek]

Hi,
I use tabs on my 53 for several reasons.
1) In a choppy head sea with 4-5 footers on the nose I put the tabs all the way down to help keep the bow down.
2) Running down the wave field in 8-10 footers at 25-27 knots I make sure the tabs are off to prevent ploughing as you drop off the back side of the wave (fresh water waves being a bit steeper than salt water)
3)I have the 675-D12's. The trim tabs give me an extra 2-3 knots on the top end in smooth conditions.
This could be due to a heavier than normal weight bias toward the stern.
- The D12's seem to weigh the boat 3-4 inches lower in the water than my neighbor's 53 with the smaller engines.
- An extended swim platform allows me to put a 12 foot dinghy with a 30hp motor mounted on the stern. (add 1,000 lb)
-Extra house batteries in the stern add about 500 lb.
Despite the rear weight bias, I only use tabs when getting on plane with full tanks.