You need more horsepower thenOriginally Posted by Crunchy
You need more horsepower then
With two motors on the Vag it felt to be affected by slower speeds when in rougher water. Like you I wished the stern to be higher and the nose lower to better penetrate waves.
The foils that were fitted to both motors lifted the stern about an inch or so and after getting used to them being in place Seafarer fitted a set of trim tabs. These even when up and level with the bottom have added to the stern lift. One of the benefits has been a marked reduction in spray blowing into the boat and onto and under the seat which also wet the batteries and oil storage.
The tabs fitted were only 9 by 9 Lencos as that was what was recommended. Playing with them soon after they were fitted it seemed that it would be possible to tip the boat over if only one was dropped. That feeling led me to accept that the size was adequate.
Even with the tabs up and no doubt with the foils in place the motors hardly need to be trimmed in to easily plane the boat.
The bigger tabs will certainly gain greater lift. Would a set of foils on the motor also give benefits? Mine are above the surface of the water when the motors are trimmed out so no extra drag has resulted and the foils do their thing at lower speeds when they add to stern lift.
Its all about trial and hopefully limited error isn't it.
Cheers
Chimo
What could go wrong.......................
Permatrim is already fitted Chimo. Took it off briefly after fitting the tabs. Promptly put it back on after the first snotty day. After much experimentation i have found peak low speed economy to be achieved by using tab angle to get the bow down thus allowing the thrust direction to be optimised for forward motion rather than lift. In heavy weather I was regularly running around with full tab down on at least one side. Curiosity got the better of me wondering whether there would be a drag reduction by running a larger plane at less angle
. So far so good.
With Lencos or Bennetts there is a lot less drag than with the other type.
Peter Webster tested the speed reduction / drag increase on one of his boats with the other type a while ago so you could conclude that lengthening the hull, in this case using trim tabs, has a positive affect once one is moving and less down angle (lift) is needed as speed increases.
Foils do similar but can create drag if you cannot lift them out of the water by trimming the motor back as speed increases. Another reason to have motors as high as possible.
I set up an Al 5.6 m boat I had years ago so that it would turn hard at speed when water skiing in fresh water but if you did the same turns in salt the prop would ventilate / cavitate as the boat sat that much higher in the salt water.
What could go wrong.......................
Yeah, try pulling the anchor up first next time Crunchy
You need more horsepower then
Mate, I don't want a cat sitting in my garage doing nothing and looking at it all day long?
The other week I was in a crappy head sea and thought "Thank Christ I don't own a cat!!!!" and wish you were in it with me
Yes, all boats have good and bad and maybe my next boat will be a cat - well, one day if I can ever sell mine ( Or give it away ) when I decide to depart with it
.
Oh no Tony,
I want to do Miami Boat Show.
Coming?
Jason would rather sit in his shed and look at his pussy all day long
When I heard you guys were off to the US, I assumed you were taking Moejoes down to the Fort Lauderdale boat show to pick up a cat cause he loves yours so much
can you please take some photos
I had the same idea for a long time now but can't make my mind up on how to fix the bigger plate to the existing plates
do i weld it on or to bolt it on
Am away from the boat for a bit MyWay. A mate knocked the plates up for me out of some 5mm aluminium he had laying around from the last boat he built. I have utilized the existing actuator bolt holes and drilled a couple of new holes about 15mm from the leading edge corners of the existing planes and used countersunk head metal threads and nylocks. Only thing you need to make sure of is that the added plate is not so far forward that it fouls the transom at full tab down. Apart from getting the plates in alloy at the right price I didn't want to attach them permanently - at least not initially - just in case it was a brain explosion rather than a brainwave so to speak.
Perhaps you should have mentioned that a few months ago, would have saved me $1200 on a new winch motor, chain and rope!Yeah, try pulling the anchor up first next time Crunchy
I did a similar mod to the Bennett tabs on my cruiser, albeit on a bigger scale - from 26 x 12's to 28 X 15.5s. I also had the plates bent up with 3 inch drop fins, just like the Bennett aftermarket bolt ons. I had the larger plates stitch welded to the existing tabs.
The difference is naturally most obvious at slower speeds and can now semi-plane down to 12 knots with the tabs fully dug in and despite this fuel economy has improved at these speeds as the boat isn't plowing. I also run the Mente Marine auto trim tab controller for tab automation which shows the new tabs are generally fully retracted at normal planing speeds.
A pic and plans of my tab mods showing the sizing and features. The larger tab plates were sized according to the Bennett recommendations for heavy arsed boats.
If you 'got the alloy plates at the right price' scotty, get another set and have them turned down at the sides like juggernaut has done, as you will get better results again - greater lift again and not at the expense of the drag as would be found from flat plates.
Minn Kotas tab plates are like this, albeit with a centre 'bulb' as well for even more lift (from greater surface area generating more lift). Awesome performance, really stoked with mine over the last ~9 years (soon anyway).
Just make sure oldmate uses a decent bend radius when he turns the sides down though in 5mm, else if too tight your side drop fins may break off one day [emoji16]. 3mm ss would give better results I reckon, but turn up the trailing edge for better lateral stiffness/strength (like juggernaut has done). Happy days [emoji16][emoji6].
Cheers
Brendon
Sent from my iPad using Ausfish mobile app
I did think about it Brendon but as the Victory's transom is not square to the water flow and I couldn't be bothered fabricating mounting wedges to rectify it, decided not to bother. Not sure how much drag they would generate but it would have to be some.
20170814_130701[1].jpg
Yeah ok didn't realise the Victory transom was not square, the fins would also give you extra steering then too... maybe not so good [emoji16].
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It may not be apparent, but the transom is not square on my boat either. Bennett supplied the tabs to the original boat (SeaRay) and are in the shape of a paralellogram. The original tabs had a bent down fin on the outer and a turned up fin on the inner. The larger tab mods by myself followed the original parallellogram shape with added 3 inch drop fins. The drop fins also keep the boat tracking straighter at slower speeds too. Tom McGow (Bennett) chimed in on the trim tab mod threads on clubsearay.com.au. which is where i gathered most of my data before spec'ing my own tabs. IIRC the drops fins are akin to going from a 9 inch chord to a 12 inch chord tab. He also mentioned the drop fins have the biggest effect on smaller tabs and tabs with longer chords.
Tom (Bennett) doesn't condone the use of tabs with greater than a 12 inch chord due to the stress placed on the single actuator setups principally when backing down and building up pressure on the top of the tab and snapping the actuator shaft. For this reason he recommended going a wider tab rather than a tab with a chord longer than 12 inches. Although I saw some of the mods where 18 inch (and larger) chord tabs mods were used without issue. In any case, the auto trim tab controller I have auto retracts the tabs when off the plane so they are fully retracted when I reverse into the pen or backing up when anchoring thereby overcoming the potential issue.
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