Hi Stu
That is on a Vagabond too isn't it?
Enjoy Jaffa!
Cheers
Chimo
Hi Stu
That is on a Vagabond too isn't it?
Enjoy Jaffa!
Cheers
Chimo
What could go wrong.......................
You bet I will. Been too long already. Promise to send a pic if the weather gods dont fight.
will send one anyway.
cheers, Stu
Chimo, Thanks for the offer to sent the photos as I think it will be easier to describe to Bennets.
Bennetts just replied to my email asking for the widest part of the wedge, I guessed it was 20-25mm on the outer edge and nothing on the inside. Johncar does that sound about right to you ??
Stue2, Great news about getting them on, would be good to see your setup. Is it possible for you to take some photos showing how far the Tab points out towards the side.
Cheer
Brett
Brett
It just occurred to me that if you are fitting tabs to a Vagabond, which I think you are and you are suggesting that the tab points out towards the side rather than in line ie parallel, with the keel then you are trying to fit your tabs too far out from the keel ie not parallel, on the curve of the transom. Refer to my second pic in post 3 above.
Cheers
Chimo
What could go wrong.......................
Chimo, This photo of yours shows the angle I am referring to. Notice the angle where you mounted your Tab is different to where the motor mounts, If you put a straight edge on the transom where the motor is bolted and compare that to the Tab mount.
The Text is a bit hard to read and the angles are not correct but gives the idea.
Red line is parallel to the back edge of the Trim Tab
Blue line is Parallel to the Transom (where motor bolts on and 90 degrees to the Keel)
Attachment 66494
It also shows why Johncar adds the wedge to the Transom to square up the Trim Tab to the Keel/Transom.
Cheers
Brett.
Yeh mate I can but it will be a day or two.Originally Posted by fishfeeder
Hi Brett
Notwithstanding the angles you have indicated that I need to go look at in the light, the tabs work a treat, do what they are supposed to do and after some 5 or 6 years are still to fall off.
I'll have a look tomorrow, in the meantime it still seems that your over-thinking this, given the way I had mine fitted ie ("Lindsay please fit trim tabs to the Vag as per your recommendations " end quote) and results I have got.
Cheers
Chimo
What could go wrong.......................
Brett, I know there is a chat board specifically for Bennett trim tabs, I did have the site bookmarked until my PC died and had to buy a new one. This site was also mentioned in one of hte threads on this site some time ago but once again I am struggling to find it. The respondants are Bennetts staff and were quite good. I am spending some time trying to restore my lost data and if I find it I will certainly post it here for you.
Hi again Brett,
The discussion about the angulation of the tabs away from the long axis of the boat is quite interesting. you are also correct that the mounting section of the transom is some degree away from being perpendicular to the long axis as it is angled fore to the motor mounting section in the middle.
It may also be worth noting that the toe out effect thus formed is further complicated by the fact that the tabs are angled in the other plane too such that the edge closer to the motor has a greater and earlier effect than the outer edge.
You might again look at the photo from my earlier post which shows that despite all this ,the long axes of the tab and the chine are still almost coincident.
Despite all this I think that the overriding consideration is that you can go and physically put your hands on a number of units right here, that have worked for many years and many hundreds of hours, when they were simply bolted straight on the old transom.
You are very welcome to come and take a look any time ,and I am happy for you to give the old girl a run and put the tabs through their paces before you decide whats best for you.
After all the thoretical stuff is settled , I reckon the K.I.S.S. principal is a good one to live by.
Let me know if you want to go for a ride anytime
Brendan
Guys,
Sorry to step in late here. I went through this exact problem about 4 months ago when I fitted Bennetts to my Victory.
Dont fit the M120 tabs. You must go for the flat tab and you wont have a problem with the downward facing wing of the M120.
When I realised the problem I emailed a guy from Bennetts and he confirmed I would be better off with the flat tab rather than mounting the winged M120 tab and a fillet. Ended up exchanging the M120 for the flat tabs.
Cant remember the size of the tab (possibly 12x12) but I can get some photos of my setup if you wish.
I went with the extra short rams and fitted the rams under the platform. I had to modify the connection point in the tab but this is not a really big issue.
Very happy with the result and there appears to be no real distubance in the wake from the tabs. Tabs work perfectly and response is excellent.
Also went for the trim indicator which I think is a must. I try and run with my tabs up as much as I can to limit drag and increase fuel efficiency. Without the indicators I dont think I would be able to tell how low the tabs are unless they are causing a fairly noticeable impact on my speed or the bow seems to be hanging low.
Cheers,
Dean
[quote=Deanom;1272554]Guys,
Sorry to step in late here. I went through this exact problem about 4 months ago when I fitted Bennetts to my Victory.
Dont fit the M120 tabs. You must go for the flat tab and you wont have a problem with the downward facing wing of the M120.
What is the "problem" that you were anticipating.
I havent noticed any problem with the wing itself.
In fact I am surprised that with them attaached in such a way they just go and do what there supposed to. But good to see that most people end up happy with thie setup.
PS .I agree wholeheartedly about the indicators . (and I am sure that comment will open yet another can of worms from the significant group that disagree. )Anyhow , each to his own
Brendan
Tenzing,
The problem with your setup is the downturn wing not being parallel to the keel which must cause a loss of efficiency (think snow plough).
The batwing shape of the M120 should only be installed parallel and for our sterns between the pod and the chine, this is not possible unless a fillet is added.
I am surprised that your tabs were installed by seafarer. They should of known better.
For your reference, here is the transcript of the email I got from the Bennett representative.
My Email:
" I have just purchased the M120 trim tabs for my 6m Seafarer Victory (Australian fibreglass trailerable boat). On setting up the tab against the rear of the transom, I have noticed that due to the rear transom being stepped, the transom at the chines is about 5 degrees offset from being square to the keel. Due to this I anticipate there maybe a drag/inefficiency issue with the downturns on the tabs. As I do not wish to go to the extra hassle of glassing in a tapered filet, am I better off to return the M120s and swap for the 30cm x 30cm flat tab to avoid the problems with the M120s. What would you recommend."
The response:
"Thank you for contacting us with your situation and yes swapping out the stainless steel trim tabs & mounting plates to our standard 12 x 12's would be your best choice to complete the installation.
If you have anymore questions, please feel free to contact us again.
Regards,
M.J. Thomas
Account Manager
Bennett Marine, Inc.
550 Jim Moran Blvd.
Deerfield Beach, FL 33442
Service hours: 8:00 am - 5:00 pm Monday - Friday (EST)
Phone: (954) 427-1400
Fax: (954) 480-2897"
Thanks for the transcript.It is spelt out quite plainly by them isnt it.
I was aware that this was their position and I agree on a theoretical level about the efficiency.
On the practical side the tabs will always cause some loss of efficiency due to their drag coefficient ,be that larger or smaller, and mine have been on for 300 odd hours and the loss of efficiency, i would say, has been quite minor( if at all noticeable)
Anyway its all good info, I still think though that even if it works for the wrong reason , it (mine) still works.
Thanks for the info
Brendan
Brett
I've had a similar issue withM80's on the transom of my Signature. Only I had to contend with a space of about 50mm on one side, plus a curved transom and a significant back-slope. The transom from hell!
Have a look at what I did at http://s853.photobucket.com/albums/a...view=slideshow
(Photobucket are fixing some problems so you might not be able to access them immediately. Send me a pm if you like and I can email photos to you)
Deanom, you told Bennett that you didn't want to use a tapered fillet, so the best solution was not to use the M120's, which have the "batwing" profile. Bennett have said on other posts that it is important for "batwing" tabs to be perpendicular to the keel-line, as the edges of these are bent 90degrees to the plane of the tab, ie they act like side fins. If these fins aren't parallel with the waterflow, they will be very inefficient. The normal tabs are just flat planes without fins, so it doesn't matter if they aren't mounted exactly parallel to the keel-line. So they aren't saying you can't use m120's on an angled transom, it's just that you should use a shim if you do.
Last edited by MikeyS; 13-04-2011 at 01:57 PM. Reason: typos
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