trim tabs - Page 3

Charles · 07 February 2003, 16:36

Now is that not a suprise.... I too was all on my lonesome bombing around Jersey, fairly flat, but quite interesting through, some nasty bits as the tide started ebbing. After all the talk about trim tabs I started playing with mine

(Don't be rude, THE TRIM TABS) and 'buried' the nose completely, a huge wall of water hit the screen and went over the top. Trimming it 'out' too much, the bow went sky-wards.... not very nice! Brian, I reckon yours is not set-up properly or you have a malfunction somewhere. Yes, Alan P, I remember that day up the Hudson, April 7, I think?

PS, Anyone who knows Jersey at all there were 40/50 dolphins just off Elizabeth Castle, near the entrance to St.Helier, absolutely fantastic.

PPs Brian, do as Julian suggested, also, put you dry-suit on and stand on the trim tab and gently push down and release a few times. Could be stuck.

seafariskye · 07 February 2003, 21:42

I started playing with mine Trim Tabs that is Charles.

I reckon that allot of people have trim tabs fitted, and not allot of people use them?????

This could say 2 things.... one they are not important to the handling of your boat, or 2, you do not know how effective they are if you do use them...........

To have the capacity to bury the nose of your boat is a major thing, using trim tabs alone, then also the capacity to change the position of your bow in a certain kind of sea (head on ) can make all the difference, on any size of journey, on any size of boat?

Reckon the original question of 'should i fit trim tabs' is answered, the difference they can make is big - no doubt.

Fit them, if you can afford it, and they are there to use if you need them, if not don't use them, as i reckon allot of people do not.

Pete F

Brian · 08 February 2003, 10:44

I have had a reply from Mr. Bennett's Tech Support overnight that says:
-20 degrees of movement is about right
-2 inches extension of the ram pistons is also about right

HOWEVER...
I am not convinced.

Just about everybody else on this forum says they can stuff their bows in flat water. My bows are about 4 - 5 ft. off the waterline at rest and I have never been able to drop the bows to that extent. Never anywhere even near it.
I am sure Alan W. will agree with me that Cyanide's tab usage has always been far more subtle?

Soooooo.... I have decided that a major investigation (out of the water) is necessary.

Huge thanks to everyone on this forum for their advice. You have convinced me that I probably have a problem I didn't even know I had !
Ribnet scores again! Love it !

Alan · 08 February 2003, 11:04

I certainly cant recall being able to effect the change in trim and attitude that Mark and Charles seem to be able to do. When using tabs to correct lateral trim in a cross wind I seem to remember that tab amounts of 12-16 degrees on the indicators were needed. In a head sea we would tab down 8-10 degrees?
Sounds as though its worth checking next time you have the boat out of the water for sure!

Alan

crazyhorse · 08 February 2003, 11:06

Well Brian I am no expert on trim tabs,but Before you consider a expensive out the water jobee,are some people saying they can drop the Bow of there boat so far as to meet up with water comming over the Bow tubes on flat water?.This does sound to me a bit exesive,as water over the top of the Bow from trim tabs alone would indicate a compleatly different profile of hull and a massive extreame in handling and economy?.

If it is so then maybe there hull really does need them as there cant be much boyancie up front? as such a small item can abviously change the hull profile by so much.Far more than you will ever get from the trim and tilt of a outboard.

I am having them fitted to our boat and expect to be able to set the boat up for different conditions in a fine tunning mode,not for changing my hull and drag profile to exesive angles such as has been descibed here and tipping my nose under,but if thats what they can do then so be it.?

Brian Im not sure whether you do have a problem with Trim Tabs here or whether otheres may have a problem with forward boyancie or weight distribution?could that be I dont know.It will be interesting to see.I am no expert but to put the nose under with a tube on the front using tabs alone seems quite an achievement to me,I would think?.

We can wave goodbye to each othere bye tipping our noses under when leaving the rib .net meeting.

Its great on here.

Good luck

matiboy · 08 February 2003, 21:06

some more science

http://www.hotribs.com/04features/features.htm

crazyhorse · 08 February 2003, 21:26

Trim Tabs Yes or NO

Who cares any more cos I dont.

They Seem like a good buy to me.

dgpw · 14 February 2003, 14:28

Has anyone used smart tabs, if so how do they work and are they any good.

crazyhorse · 15 February 2003, 17:08

Dont know dont care anymore as the trim tab debate ended in imformation overload.

.

Mike Garside · 16 February 2003, 07:22

At the risk of adding to the information overload, here's a couple of quickies gleaned from my experience of installing trim tabs on Magellan Alpha.

1 When I bought the boat it was underpowered and stern heavy. The trim tabs transformed her. She popped up onto the plane dead easy.

2 When I installed 2 new fuel tanks of 600 litres further forward and changed the engine for one almost twice the power the boat popped up onto the plane without the use of the tabs. Good boat rim plays a vital role.

3 I now use the tabs for small ride corrections, particularly in a beam sea. Depress them too much and they slow the boat. On flat water I lose about 3 knots at WOT with 10 degrees of depression.

3 The trim tab mechanism is quite delicate. The ram tubes on the Bennetts are plastic. Standing on the plates sounds risky to me. Brian, they are probably fouled from the muck in that marina of yours. A careful wipe down on the piston rod that attaches to the plate could be all it takes.

Cheers....

niels · 17 February 2003, 13:38

thanks for all your comments.
I hoped for some answers but I didn't expect so much replies.
I think I just try them.
Does anyone know a good brand (price/quality)?
Bennet? Trim Master? Lenco?

Again thank you all

(poor english language) Niels

niels · 17 February 2003, 13:40

sorry

John Kennett · 17 February 2003, 19:10

Niels

I don't know much about the different makes of trim tabs, but judging by that photo you ought to start by just triming the engine in!

John

niels · 19 February 2003, 09:05

thanks John, but this is not how she normaly runs. This was just for fun.
My problem is that at full speed(59knots) the boat is going from left to right bouncing(don't know the name for it).
I was told that for fast boats I have to place the tabs horizontaly.
Do you know anything about that?
It sounds strange in my ears.
thanks
Niels

Julian · 19 February 2003, 09:36

Hi Niels

Basicly because the boat is light you are suffering from chine walking. Our old boat used to do this. To solve the problem Alan Priddy to a chain saw to the deck and we fitted larger fuel tanks in the bow. We turned a very bad humber into a good sea going boat. I 'm not sure how much effect you will get from trim tabs as the boat is obviously light.

Julian

niels · 19 February 2003, 15:05

It weights about 1000 kg with motor etc. I don't know if that's light or heavy. I have already a 220 ltr tank in the midle of the boat, and am a little afraid to take a chainsaw. But thanks anyway.
Niels

jwalker · 19 February 2003, 20:25

A chine walk often happens when the boat is lifted high in the water, as it is at speed. Due to the natural rocking of the hull on the water, the engine leans over to the side and drives the hull harder to that side. The slightly tipped hull generates more lift on that side and it promptly rights itself. But, because of inertia, the hull travels past centre and onto its other side. The engine then falls over to that side and drives the hull also to that side. Lift is generated and the boat comes back but it now has a little more inertia and falls back over to the first side. This cycle is repeated and increases in effect at each oscillation. Anything which helps to keep the engine under control will be good. Very tight steering with as little as possible free play will help as will more rigid or even solid engine mounts. Solid engine mounts though are not really suitable for leisure use. As indicated in the previous posts, adding weight to the bow will increase the wetted area and this can increase the stability, but there is a limit. A nice straight hull with sharp, clean edges will also help.
JW.

niels · 19 February 2003, 20:53

wow!

Lester McCarthy · 20 February 2003, 09:00

I have recently test driven a 7.5m rib fitted with a transon lift allowing a 7 inch stroke limit. Out at sea in a 2ft wave height there was no noticable difference in performance in the 50 - 55 mph top end range. In the sheltered confines of the harbour a small amount of hull lift was noticed at around 53mph

With reference to trim tabs, if you replace your old manual "pull out the peg and drop it overboard", with an outboard with electic trim you will not need to fit trim tabs. Go for a 50hp Yammy and your Flatacraft will go like a rocket.