Quinnie 560 vs Yamaha 4-Stroke 80Hp

Hi guys new here!

Have a bit of a problem.

I just purchased a Quinnie Classic 560 Runabout 2000 model millenium hull matched to a 2005 Yamaha 4stroke 80Hp. It has a 17pitch prop with no hydrofoil.

The hull needs alot of work and im currently in the middle of a total strip down repair and respray back to the factory paint and decals.

I took the boat out for a test prior to starting work on it. Im under the impression the boat is underpowered and need some opinions please.

With just myself in the boat and 20L of fuel it planes easily and hits 5200RPM at WOT with the right trim ajustments. With 4 people it still planes easily but speed is hampered and I get the feeling the engine is working too hard. It only hits 4700RPMS at WOT no matter how you trim it. I can only imagine the strain with a full load 6 people. Its lugging.

Hull plate reads 495kgs hull weight max HP 115.

I was wondering if going down to a 15pitch would solve the problem. I was told by a marine place today that the engine would be much more responsive with a full load and probably hit 5500RPMS. With a light load it will hit 6000rpms which is what its rated to. (5500-6000) factory specs. I guess a hydroil ontop of a prop change might solve the problem ? Im thinking 14pitch.

OR do u guys think its underpowered. Worse case i might have to trade in the engine in for a 100 or 115 4stroke yami which i would like to avoid $$.

Thanks in advance Robbie.

Re: Quinnie 560 vs Yamaha 4-Stroke 80Hp

At 4700 RPM loaded your well overpropped. You need to adjust pitch to hit the upper half of the band (5500-6000) at heaviest expected load. That may mean a 13P. Ask your dealer if you can test and return props until you find the right pitch. It's been my experience that if you enjoy entertaining friends on your boat your better off with the highest rated power. On the other hand if high performance is further down on your list the 80 can be propped to perform better than it now does.

Re: Quinnie 560 vs Yamaha 4-Stroke 80Hp

At 80 hp your at bare minimum for that boat; 85 would be closer to the minimum.
At 17in. your over propped and you can see that because your not reaching your rpm band.
Rule of thumb about 200 rpm for one inch pitch change.So it would seem
a 13 in. pitch would get you about 6,000 rpm.If it seems to over rev just throttle to the max reccomended.It will jump on plane and handle a load much better.As suggested sometimes a dealer will let you test for the best prop.Don't mess with a foil.After you are all set with your prop;
fine tune the setup.You may be able to raise the motor a little and gain a little more performance.Just be sure it pumps water.If you still think you need some help try something like smart tabs.

Re: Quinnie 560 vs Yamaha 4-Stroke 80Hp

if you have a boat that is slightly under powered get what i call a barge wheel, larger diameter and less pitch, i think you should be able to put 14"p on that motor, and then adjust your pitch accordingly, don't under estimate diameter it will shove a heavy boat pretty well.

Re: Quinnie 560 vs Yamaha 4-Stroke 80Hp

seabasser said:

if you have a boat that is slightly under powered get what i call a barge wheel, larger diameter and less pitch, i think you should be able to put 14"p on that motor, and then adjust your pitch accordingly, don't under estimate diameter it will shove a heavy boat pretty well.

Click to expand...

Not a bad idea but::
I don't think we're talking about a big heavy boat;just a boat that is slightly
below the minimum hp reccomendation and propped wrong.

Re: Quinnie 560 vs Yamaha 4-Stroke 80Hp

oops i meant 14" diameter not pitch....that being said when talking about carrying different amounts of weight, like boating alone or adding 6 ppl a wheel with more diameter and less pitch will be more consistent, the weight will not kill the rpms as bad. maybe lose a little off the top end empty but i don't think this was a speed boat anyhow.