Trim Tab positions?

Dan · 30-03-2005, 09:20 AM

Just been looking on the bennett site and it shows the fitting of the tabs running in line with the V, going across the strakes, yet most of the pictures that I see, the tabs are positioned horizontally. In peoples opinion which is most benificial or does it not really make to much difference?
Cheers
Dan

Cyco · 30-03-2005, 09:34 AM

Dan I was going to post a similar question very soon as I need to fit a set on Badboy.
Most of the tabs that I have seen have been fitted hozizontaly
but I don't know for sure which way is more efficient.
Some of the bigger Bernico that I have seen have them angled.

Cyco

mike k · 30-03-2005, 09:42 AM

Don't know for sure, but I would have thought horizontal, so that when you operate them they push down and not out, minimizing any steering effect .
Although when you operate them together they cancel each other out!!!!!!!! but hey what do I know.

Matt · 30-03-2005, 10:04 AM

I'm sure everyone will have a different opinion on this one.
Personally, I would mount the tab in line with the hull bottom, it angled as per the deadrise.
When the tab is down you are getting the greatest wetted area on the tab. Mounting the tab horizontally, I would guess, will reduce the efficiency of the tab since the outer edge will effectively be 3 or 4 inches higher (depending on the deadrise) and not effective operation at small deflections of the tab, so you end up using more tab which will be less efficient with a greater angle of attack.
I would also always go for the longest possible tab, a) to reduce the amount of deflection needed to create a given force and b) so that in a neutral or below position it is increasing the effective length of the boat, which I reckon is a good thing in the rough.

Matt · 30-03-2005, 10:15 AM

And, should it be mounted so the leading edge is in line with the bottom, or raised slightly? I am wondering if having it in line with the bottom means that at slight negative deflection (ie raised) it could actually create bow lift (like the arneson rocker plates). But on the downside, it'll always be 'wet' which could add drag, whereas raising it an inch or so means the tab when fully raised will be completely clear and not adding any drag?

BluFin · 30-03-2005, 10:18 AM

I'd go with Matt on this. Otherwise you are only using the outside corner of the tab which seems a bit daft have a look at the tabs on offshore only under the classified section, look at the transom pics here you can see they are all pretty much as matt states.

here is the link

http://www.offshoreonly.com/esvon/ca...0caa693985ebdd