Do you use trim tabs or a hydrofoil/stabiliser on your boat?
Ive been slowly doing up a 19ft voyager thats got a 125HP Mercury 2 stroke (2+2 cylinders) on the back. I do alot of Km's out there and I estimate that it uses just under a litre per kilometre with 3 blokes, 150litres fuel and our fishing gear cruising at 38km/h (approx 4000 rpm) (the hull is late 80's and seems pretty solidly built and heavy) I would like to reduce the fuel consumption if possible so just wondering if i was to fit trim tabs or a hydrofoil/ stabiliser or both will it make a significant difference in fuel economy? I keep reading all the advantages of these, do people find they are worth it. The boat cruises at 12 km/h on two cylinders (approx 2500 rpm) and when the other two cylinders kick in at 2600 rpm or more it jumps straight up onto a plane so maybe trim tabs and hydrofoil/ stabiliser wont make a difference? Also what about props if you change them can you reduce fuel economy? All advice appreciated Cheers Dave
Paul H
Posts: 2104
Date Joined: 18/01/07
Trim tabs can be useful for
Trim tabs can be useful for many things including balancing the boat when running in different directions to the sea. Foils are a different thing. My general rule if you get on the plane easily dont fit a foil, varies depending on the type/size etc but they can be bad in a following sea as they allow the following wave to push the back of the boat more and add to broaching problems. That being said I have one and don't have a problem but know how to drive to the conditions in following seas
Must add mine is a pain when trolling too as it wants to jump up on the plane and maintaining a trolling speed can be difficult
Hope that helps
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carnarvonite
Posts: 8673
Date Joined: 24/07/07
Last resort
They are an absolute last resort to fix something that can't be improved by some other method.
As Paul says , in a following sea they provide lift on the stern of the boat at the time when its exactly the thing you don't want, in many time causing the boat to broach and likely go over.
Jeff Hugo
Posts: 48
Date Joined: 14/09/09
Trim tabs
we have trim tabs on our glass boat and have to say they are really good.
I would not add to try and save fuel, more a case of balancing out the boat and the ability to flaten out the attitude of the boat when trolling.
As always you need to know when to use them and when not too.
They are always fully retracked in a heavy swell following sea.
Cheers,
Jeff
Jeff
JohnF
Posts: 2839
Date Joined: 07/07/10
Best economy is with trim
Best economy is with trim tabs fully retracted and motor trimmed right out to just before cavitation. OK in calm weather, but hard ride as is gets rougher. Then we trim the motor in to about half, the start lowering trim tabs to get the nose right down into a big chop.
Hydrafoil generally a bad idea, if it helps it is just masking a poor setup......broaching is THE biggest risk in a boat.......
Boston Whaler 235 Conquest......getting the flogging it was built for.
Paul H
Posts: 2104
Date Joined: 18/01/07
something probably worth
something probably worth adding with broaching. Different hulls obviously preform better than others but broaching is basically a result of travelling too fast down the face of one wave and then the bow of the boat running into the back of the wave ahead. This results in the bow stopping and the wave behind hitting and pushing the rear of the boat around until side on to the wave throwing occupants around or worse overboard, can also mean following waves swamp the boat.
The foil on the motor gives the wave coming from behind something more to push on to push the rear of the boat around hence the bad rep with them. If your boat broaches or feels like it is about to let go, slow down or change tack to angle across the waves in either direction. This may involve tacking in each direction to get where you want to go..
Some hulls will dig in and broach when running down the face of a wave without hitting the wave in front. Again slow down - better to get there later but alive!!
Cheers
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carnarvonite
Posts: 8673
Date Joined: 24/07/07
Throttle on
If you feel the boat starting to broach DO NOT throttle off, this will drop the nose and around you will go instead give it shirt, to get the nose up, straighten the boat up then slow down once you are back in control.
Paul H
Posts: 2104
Date Joined: 18/01/07
+1 meant slow down to avoid
+1
meant slow down to avoid broaching in the first place
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squidder
Posts: 457
Date Joined: 03/09/10
For what it's worth
beeroclock, I may have the same boat you are doing up, mine being a 5.8 Voyager fisherman.
In saying that , I had hydrafoils on it when I bought it and found they didn't give me the control I wanted in a following sea, so off they came and I must say I do not have any probs in any seas so long as I drive the boat as the sea allows.
I like the arse of the boat in the water which gives me good drive and control.
dant
Posts: 504
Date Joined: 13/03/13
+1 for trim tabs - i dont
+1 for trim tabs - i dont think they will reduce your fuel consumption, but will steady your boat up.
i have a 6.5m glass and they trim it up a treat whilst travelling. Works especially well if you have a couple of round mates that always sit on one side of the boat.
solly
Posts: 375
Date Joined: 11/09/05
trim tabs
Recommend them for stability and control
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