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aq 130/270 leg, i want more speed!

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welshswampy

Regular Contributor
hi all, ive not long bought a wilson flyer 20ft(cathedral hull) with an aq130/270 leg, i can only get about 12 knots max, did have a bit of water in hull and pumped it out, will this boat get up on plane or am i asking too much? as you can tell i dont know a great deal about boats, any help/advice would be greatly appreciated, many thanks in advance
 
I would expect about twice that much at least at max... unless its a "big one"... While you indicated the hull type, you did not tell us if this is a "runabout" or a mini cruiser complete with bunks, a galley and a head...

The standard questions start with..
What is you max RPMs at wide open throttle...?
 
hi sandkicker, thanks for reply, am reading this just before i go to work, it is a fishing boat with a small cuddy up front(no bunks just bench seats) and a semi-concealed helm( roof cover and side cover but open to deck area) i dont like revving much past 4000 cos im not sure that engine will take it (engine about early 70s?) however engine seems in great condition(sounds sweet and always starts). do these engines rev any higher safely? also i have a pair of solex carbs which have been set up and seem ok,
 
If the engine is an AQ130C, then you should be able to take it up to at least 4600-4800 rpm for a short period just to see what it is capable of. At 4000 rpm, my little 17' runabout that only weighs 2000 lbs with an AQ130C does about 23 knots or so, but at 4600 she does about 27. But it sounds like your boat is quite a big larger and heavier than mine. What pitch prop are you running? Even with a properly running engine, that can make a significant difference in the boat's performance.
 
i dont know what pitch the prop is, i assume it is the standard prop of a 270 leg, but i will get it checked, do you know what the correct pitch should be? thanks again
 
welshswampy said:
i dont know what pitch the prop is, i assume it is the standard prop of a 270 leg, but i will get it checked, do you know what the correct pitch should be? thanks again
Click to expand...

I found this on the web which may help:

[FONT=Verdana, Helvetica]Selecting the Right Propeller for Your Boat and Engine[/FONT]

[FONT=Arial, Helvetica]The best propeller size for your boat and engine combination is based on the recommended operating range at wide open throttle (w.o.t.) for your engine, which you will find in your operator's manual. This will be expressed in terms of a certain horsepower at a certain RPM (revolutions per minute).[/FONT]

[FONT=Arial, Helvetica]The goal in prop selection is to determine what propeller style and size will maximize performance for your boat, while allowing your engine to operate in the recommended RPM range. The correct propeller will prevent the engine from going beyond its maximum rated RPM, yet allow it to reach the minimum rated RPM where maximum horsepower is produced.[/FONT]

[FONT=Arial, Helvetica]Run the boat/motor at w.o.t. under normal operating load to determine the maximum RPM you are able to obtain. A tachometer is necessary for this test. Adjust the motor trim angle for the optimum performance. If during this test, you begin to exceed the maximum rated RPM of the engine, reduce throttle setting to a position where maximum RPM is not exceeded.[/FONT]

[FONT=Arial, Helvetica]If your test results in your being able to over-rev the engine, you need to increase the pitch of the propeller. Increasing the pitch increment by 1" will result in approximately a 200 RPM drop. If your testing shows, however, that you are only able to obtain a RPM somewhat lower than the Minimum rating given by your engine manufacturer, you would need to decrease pitch. Decreasing 1" pitch will increase your RPM by approximately 200 RPM.[/FONT]
​
Hope this helps.
 
sorry for delay, have just measured the prop and it is about 14-14 1/2 inches in diameter, and i cant see any other identifying marks on it
welshswampy said:
i dont know what pitch the prop is, i assume it is the standard prop of a 270 leg, but i will get it checked, do you know what the correct pitch should be? thanks again
Click to expand...
 
What is the RPM at WOT (Wide Open Throttle) with a normal load in the boat? That's the first thing you need to know in order to determine if you have the right prop or not. Or the lack of speed could be due to the fact that the engine is not running properly (e.g. engine not timed properly, bad points, bad spark plugs, etc.).
 
thank you for your replies, sorry i dont get back to you sooner(also for being a complete newby)i dont get to use a computer that often, i wont be able to get the boat back in water untill next weekend at earliest due to work commitments, then i will check everything you suggested and then get back to you, thanks again
 
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