crestliner kodiak with Mecrcury 50 elpto, prop questioncre

[kuba]

My props last two numbers are 12. Im assuming its for 12 degrees, looking for some performance and was thinking of getting a 4 fin SS prop with 14 degrees, worth it? Boat is 16 feet,
Thanks guys

 

[steelespike]

Re: crestliner kodiak with Mecrcury 50 elpto, prop questioncre

It depends on your present performance.If you get us the info in "read this first" at the top of the prop forum we can tell better
what should work.A Tinytach will get the rpm and a gps is best for speed.
you shouldn't make any prop changes without these things. Your motor needs to be able to operate within its
Wide open throttle rated rpm range.
This info will tell us how well its working, what might help it and if the changes result in the expected changes.

 

[kuba]

Re: crestliner kodiak with Mecrcury 50 elpto, prop questioncre

Completely forgot to mention that my boat does 30 mph or 50 kmph on the water, and also it does it at about 5500-5600 rpm.

 

[steelespike]

Re: crestliner kodiak with Mecrcury 50 elpto, prop questioncre

Prop pitch is rated in inches yours is a 12" pitch about in the middle of prop sizes.
Boat; glass or aluminum?Big deep family boat or little skipper? A guess of the weight?
Is 30 with just you in the boat?
What sort of improvement in performance do you want?
While your at the max of your rpm rating 5500 a 4 blade 14" could lower your rpm by 300 to 500.
Likely slowing the speed. Might improve hole shot and handling.
A 12" ss 3 blade might improve performance across the board.Difficult to tell how much.
Going from al to ss can be unpredictable. Ss will cost 2 to 3 times more than al.

 

[Texasmark]

Re: crestliner kodiak with Mecrcury 50 elpto, prop questioncre

Completely forgot to mention that my boat does 30 mph or 50 kmph on the water, and also it does it at about 5500-5600 rpm.

I don't know how you can change from what you have. Your rpm's are right where 2 strokes like them at WOT normal load. I guess you are running alum per your comment. As spike mentioned, about all that could benefit you would be thinner SS blades, and maybe high rake which usually lifts the bow and in doing that reduces wetted surface, hence drag, which allows your engines rpms to increase from present location. With that happening you may gain a couple hundred rpm, but you can only expect about 200 rpm change per inch of pitch change. Since standard props usually come in 2" increments, you may be looking at your 14" SS but in 3 blades, not 4 (more load more rpm drop) and your top end rpms around 53-5400 which isn't all that bad. But, unless your hot dog SS prop is ported, which a lot are, you will have a longer hole shot which your engine will not like. Ports will take care of that problem for you.

HTH,
Mark

 

[kuba]

Re: crestliner kodiak with Mecrcury 50 elpto, prop questioncre

Yes, the boat is aluminum. I will be mainly using it for fishing twice a month, and ocassionaly pulling a tube. Is 50 hp enough to pull a tube? Also, how long can I run that motor at wot? I don't want to abuse it.
It is my first power boat, I used to have a 30 foot C&C sailboat with an in board diesel

I like to improve things, that's where from all these questions about the prop came so im guessing I have an optimal setup now.
My prop has a small 1x1/2 inch deep ding in one of its blades, should I be concerned?

 

[kuba]

Re: crestliner kodiak with Mecrcury 50 elpto, prop questioncre

Forgot to say that in the boat mainly will be three people, when fishing three adults, or when playing two adults one three yearold, or in the second scenario, one on the boat and one with the kid on the 'sausage' being pulled, when pulled it will not be wot for sure due to the age of the kid.

 

[Texasmark]

Re: crestliner kodiak with Mecrcury 50 elpto, prop questioncre

I had a 55 hp Chrysler in '71 on a 16' very light tri-hull. Had wife and 4 kids. It was marginal power to pull me up on 2 skis. You are probably with the loads you specified. A picture of the ding would help. If you feel any engine vibration that would surely be a clue to fix it.

Mark