Getting up onto the plane with a flybridge boat

Nauti Fox

Nauti Fox

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Just wondered what technique you use, when we bought the current boat, Fairline 43-45 Sedan, Volvo TAMD 71B's, our largest boat to date I was told the best way was to smoothly increase the throttle until you got onto the plane, almost taking it in stages and not using full throttle. I've stuck to that and not had any problems, the boat seems to accelerate nicely and get over the hump and cruises at about 2200rpm (WOT 2600rpm).
Talking to others, some do the same as I do, others use full thottle, anyone care to comment on pros and cons and any methods in between.
 
The most important thing is to have the trim tabs down whilst the boat is rising on to the plane and then easing them off when the boat reaches your desired speed. As for the throttles, I do what you do, gradually and smoothly increase the rpm as the boat is rising on to the plane. If nothing else, mechanical sympathy requires that you do that
 
I run with the tabs down all the time except at displacement speeds otherwise it seems to run a bit too bow high for my liking, I think some of the older boats like mine do tend to ride like that.
 
Nauti Fox said:
I run with the tabs down all the time except at displacement speeds otherwise it seems to run a bit too bow high for my liking.
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That is one consideration but there are two others, firstly what tab position gives optimum speed and secondly what tab position is suitable for the prevailing sea state. Depending on the hull, most boats give a more comfortable ride into a head sea with the tabs down but the opposite is true in a following sea when you really want the bow as high as possible to prevent a broach. The latter is only a risk in large seas but most planing boats do track straighter in a following sea with tabs fully up
 
Thanks Mike, as regards speed, it seems to make little difference, I don't know whether the bow up syndrome is because this boat is heavy, ex med, so has two a/c units, 3 cylinder generator, crew cabin in the stern etc and what could be considered to be moderate horsepower for the weight. I haven't had the pleasure of a large following sea to see the best tab position but I've no doubt you're right.
 
Nauti Fox said:
Thanks Mike, as regards speed, it seems to make little difference, I don't know whether the bow up syndrome is because this boat is heavy, ex med, so has two a/c units, 3 cylinder generator, crew cabin in the stern etc and what could be considered to be moderate horsepower for the weight. I haven't had the pkleasure of a large following sea to see the best tab position but I've no doubt you're right.
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TAMD71Bs sound about right to me for the size of boat. What will she do flat out? 28knots? Some hulls respond more than others to trim tab position; it sounds like yours is one of those that doesnt
 
About 26 with three quarter tanks and full water, cruise speed varies between 20-22kts (2100-2200) rpm depending on weight in reasonable seas.
 
Nauti Fox said:
About 26 with three quarter tanks and full water, cruise speed varies between 20-22kts (2100-2200) rpm depending on weight in reasonable seas.
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Are the engines pulling their max rpm (2600rpm?) or slightly over at that 26kt top speed?
 
I generally smoothly increase the throttle on my 43' Nimbus, and she comes up steadily. I have the Humphree Interceptors set on Auto, and they seem to adjust as needed.

If it is a head sea, I often give a little more trim, but the Auto system usually takes care of things.

Another gadget to upset Nick Burnham?
 
Deleted User said:
Are the engines pulling their max rpm (2600rpm?) or slightly over at that 26kt top speed?
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Spot on 2600, I haven't checked the pitch of the props, perhaps next time it's out of the water. it's a 91 build boat so they must have been replaced at some stage.
I must admid I very rarely run at WOT.


70036418_10217493432505255_3462779410594136064_n.jpg
 
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Smooth power or power in stages. I will make up percentages as I have no ideas where the levers are but 25% ( ie it is moving but no on plane ), then I want it to go so unto lets call it 85%, and then as soon as it is up there and accelerating pull it back to 60/70% ( I tend to cruise at 18-20 knots.

You could just slam it to 100% but the load increases radically and I don't really see the point.

On mine the main thing that makes it plane is the turbos cutting in and spooling up. as soon as that happens you can slack off a few moments later ( unless you wish to drive like a loon)
 
Local Volvo guy recommends full throttle then back off. Apparently it saves fuel - I seriously doubt that.
As per others I like to let the boat accelerate in it's own time feeding in more power/revs as it goes - just in case something goes bang. I tend to do it in stages, 900 rpm in/out the harbour, 1500rpm, then 3200rpm
 
Nauti Fox said:
Thanks Mike, as regards speed, it seems to make little difference, I don't know whether the bow up syndrome is because this boat is heavy, ex med, so has two a/c units, 3 cylinder generator, crew cabin in the stern etc and what could be considered to be moderate horsepower for the weight. I haven't had the pleasure of a large following sea to see the best tab position but I've no doubt you're right.
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I had the same boat some years back, and it also rode bow high. I think it was just the hull shape. If I was really light and just anti fouled I could get about 28 knots. At that speed it did flatten out a little - like in this photo

69851577_10157257414126343_2066204583083900928_n.jpg
 
By way of comparison, my displacement speed is 6 knots at around 1500 rpm.

To get on the plane I open up to around 5,000 rpm which rapidly gets over the hump then ease off to cruise at 19 knots at 4,000 rpm. The outboard is supercharged so pretty instant power is available.

Should I wish to increase my carbon footprint and reduce my bank balance I may go to WOT at 6,400 rpm @ 35 knots for a few minutes....
 
Aquastar 48 twin TAMD 63P 370 hp 18 tonnes displacement.

Assuming I am not tight for time, out of the harbour push up the RPM, stick at about 1500 rpm so burning some fuel and heating up , when I see the temperatures start to climb I take her up to 2500 Cruise RPM.
 
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