Losing speed and running at higher RPM than normal on SAN 210 - HELP

[Coygiles91]

Super air nautique 2005 - excalibur 330

My boats perfect pass is set up for RPM and wont run with it on MPH, this is how i noticed the problem... My boat would normally run 22 MPH at around 3000 rpms with my ballast full. I took it out in the morning and put my boat up until my afternoon set. Once i took it out in the afternoon my driver set it to the same RPM range as normal with the exact weight as before but my boat wouldnt reach the speed it normally did. I had to run it around 3400 RPMs instead of 3000.. wind was not a factor... Boat sounds fine and i changed all spark plugs. Im wondering if its a prop? (prop has no visible damage)..

Has anyone had this problem before that can give me some advice??????

[t.franscioni]

It used to run 22 mph with your configured ballast and rpm set to 3000, What speed does it run now under those conditions?

[Coygiles91]

Its now having to run at around 3400 rpms to maintain that same speed

[Coygiles91]

at that 3000 rpm range I'm running like 17-18 but it used to be 22mph

[t.franscioni]

if something was in fact mechanically wrong I would think it would have to be your tranny slipping because that's the only point in your drivetrain where the engine rpm and prop rpm can change in retaliation to one another. Check your tranny oil and see if it's really hot after you drive around with your boat loaded. If it's really hot then your clutch is slipping and or tranny cooler is clogged or not operating correctly. Loading these boats with tons of weight is really hard on the transmissions which is why it's so important to have the prop if your going to weight your boat down heavily.

[t.franscioni]

Important to have the correct prop if loaded heavily*

[Coygiles91]

My boat has pretty low hours and the tranny has been maintained so I wasn't thinking about it being the problem, thinking its the prop..

[t.franscioni]

given there is no prop damage it doesn't sound like your prop is at fault for the change in rpm, something would have had to change to be getting these different rpm results and the only thing that can change a prop is damaging it as far as I know. Yes moderate temperature is normal for trans so if that's what your getting when you check the tranny after a long set under full ballast then that's a good sign. Does the engine sound good when your wakeboarding with full ballast?

[t.franscioni]

Do you wakeboard on a river? Like wind, current can change your rpm/speed correlation. Do you use GPS or paddle wheel perfect pass?

[Coygiles91]

I wakeboard on a lake in a cove with little to no wind. The perfect pass isn't GPS it's paddle wheel.

[TRIP]

Do you keep your boat in the water? I do and I have to clean the hull every couple weeks. If not, a tiny thin layer of algae grows on it which reduces top speed by about 10 miles! Also meaning I need more rpm's to drive the same speed. Plus obviously use more fuel.
If not that, maybe something else got stuck somewhere under the boat?

[t.franscioni]

Was going to say if it's paddle wheel maybe it's busted and not spinning as smoothly as it should be therefore indicating a lower speed than is actually the case BUT you would definitely be noticing 4-5 mph when wakeboarding.... Does 22 mph now seem faster than it used to?

[Coygiles91]

No, 22mph still feels 22. My perfect pass is now turned up to a higher rpm to get to that same speed with good conditions/same ballast. It went from running perfect to acting up in between morning & afternoon sets..

[t.franscioni]

Trip brings up a good point, when drag or maybe in your case power loss increases then engine must work harder to create the power needed to turn your prop at a speed of 22 mph... How many hours on your boat? When was last time you did key maintenance like changing fuel filters, distributor cap, distributor rotor, plug wires, you just did plugs recently it sounds like huh?

[Coygiles91]

Yea I was going to check out the hull next weekend.. I keep it in a boat lift.