Need info for finding the right prop

[DamianJP]

I bought a Aluminium Skeeter ZX 18 with a 1997 Yamaha 115 on it.

My first aluminum boat so mabey its my operation error.

The only markings on the prop is K-23 and I don't know if its a stock prop that came with the boat/motor package or if its a aluminum aftermarket prop. I think the 23 means the pitch is 23.

Boat and engine is a package, so I know the engine is mounted right and I can see the cavitation plate is lined up were it should be.

Boat is 893 Lbs.
Engine is 330 Lbs.

When I'm running around 3000-3500 RPMS (Not WOT, just crusing) and have the engine trimmed all the way down, I have water cresting on the sides of the boat because Im pushing the water rather than glide on it. So I goto trim the motor up little by little.

The water "crests" on the sides of the boat starts to go away and I start to glide on the water,but not fully. The water crests are still there and the boat doesnt get light on the water and glide I can still feel the boat pushing the water still abit.

So I go to trim up (alittle by little) to get it to fully glide on the water. Then the RPMS go up atleast 500-1000 RPMS more and the motor starts to rev higher and seems like the prop is slipping.

Can this prop infact be a after market prop, the K-23. And is intended for speed only? I could care less for gaining top end speed, I want to be able to cruse nice around 3000-3500 and be fully planed off gliding on the water rather than push it.

Compression is perfect , so is spark.

What prop should I be running with these weights I have given.

Also I needed to see if you guys know what ratio my Lowerunit is and to concur that my target RPM range at WOT is 5400 / 5600 RPM.


Thanks,
DamianJP

 

[craze1cars]

Re: Need info for finding the right prop

That is a Yamaha propeller, 23 pitch. It's what they call a "series-K". http://www.yamaha-motor.com/outboar...tail/5/397/1352/8512/all/1/3970/0/detail.aspx
http://www.powersportmarine.com/esh...uct_638250.Aluminum_Propellers_-_Series_K.htm

I frankly haven't the foggiest what "series-K" means, but I think it's just a fittment/hub design and has nothing to do with the blades or propeller design itself.

Sorry I can't really help you too much with your other questions. Not sure exactly what you are experiencing/describing. Generically speaking, uf you can't get the bow up high enough, look into a bow-lifting prop. If you can't get the stern up high enough, look into a stern-lifting prop.

Engine height placement is also very much adjustable. I can absolutely assure you that just because you purchased the boat as a "package", and the A/V plate "looks" like it's in the right place on dry land, this does NOT mean the motor/prop/plate is at the correct location while you are on plane, or that the motor is positioned in a place that is best for your usage and desired handling characteristics. For example, who is to say the initial setup didn't set the motor height for max top speed, possibly at the expense of mid-speed handling...and you stated yourself that your priority is midrange handling, and not top speed??? For that reason it is VERY common for people adjust motor mount location to suit their individual taste for performance. So you might be wise to try raising or lowering the mount of your engine, so you can and see how different positions impact your handling. A motor reposition might be exactly what you need...and it's 100% free...

As for whether you need to go up or down in pitch, we'd need to know what your current WOT full speed RPM is. Conventional propping wisdom says if your top speed RPMS are below your motor's range, go down in pitch. If you're above range, go up in pitch. How many inches of pitch? We'd need to know your numbers....Of course you can ignore this if you plan on never going full speed...but then you just need to experiment and figure out which works better for ya.

 

[SparkieBoat]

Re: Need info for finding the right prop

craze is right on..I would play around with lifting the motor on the transom some, maybe even getting a 10" manual jack plate, i recently raised the 110 on my 17 bass boat 2 holes and it now jumps up on a plane quicker, stays on a plane at lower RPMs, and gained almost 5 MPH, pretty remarkable difference, I got the boat last year and it ran out fine and was just like it came from the factory back in 1988, imagine 23 years of lost preformance...you also may want to invest in a set of trim tabs. they will pop you up on a plane and raise the back of your boat out of the water.

 

[DamianJP]

Re: Need info for finding the right prop

Well the engine is all the way mounted to the lowest position. Any highed and the A/V plate will be above the bottom of the hull. My RPMS are low I think around 4300-4800 RPM. And I think I should be aound 5400-5600 RPM. Someone told me to try a 21 pitch or better yet a 19 pitch prop.

Isn't the A/V plate supposed to be even with the bottom of the hull?

The problem is I cant get the boat to ride on the "pad" of the hull and smoothly glide on the water. It's like Im still pushing water rather than gliding on it. I want to get out of the hole , plane off , and then bump the speed back and do a nice cruise still riding only on the pad.


Thanks,
DamianJP

 

[Texasmark]

Re: Need info for finding the right prop

I thought I answered this last night. Did you post more than once?

 

[SparkieBoat]

Re: Need info for finding the right prop

you forgot to hit the submit button Texas...LOL Damian, 4300-4800 RPMs is a big difference, which is it? we would need to know WOT RPMs (exactly) in order to help you prop for your target RPMs. and the AV plate can be above the bottom of the hull. raise the motor 3 holes and see what happens, before you start prop shopping. if the prop vents (RPMs shoot up but boat slows down or goes no faster) then lower it 1 set of holes and try it again. it is easy to raise and lower motor at the boat ramp, carry a cement block and a few boards to put under the motor and raise/lower the front jack to lift/lower the motor. easy easy too easy. this is the first thing to do.;