New boater needs help choosing a new prop

[chucksorce]

First about my boat, 04 crownline 220 ccr (cuddy cabin) 5.0mpi, alpha 1, 21p 3 blade alum prop, 340 hours on it, use is on fresh water lake. My boat wont plain off to save a life unless I use my trim tabs to force the bow into the water and if I have a few people on it they have to get in the front to plain off, my top speed is 39mph per gps and I really don't want to loose any top end. what is the best prop for my boat? pitch, stainless or alum, 3 or 4 blade?

 

[SkiDad]

My friend had a similar boat and engine that weighed about 600 lbs less and he ran a 21p stainless and it was a little sluggish out of the hole but did it fine otherwise - He mostly did cruising with the boat. ran 45-48 mph depending on load - i always told him to get 19p so he could pull skiers.

I would suggest at least a 19p stainless - or maybe 18p 4 blade. I doubt you will loose speed b/c you are already too slow for that engine - getting your RPM up will help a lot and "might" actually go faster.

without knowing any more info that is my best guess. if you know the RPM that will help us. I bet your RPM is low. If your RPM is real low - say 3800, then I would go to a 17p.

 

[MikDee]

Tell us your max rpm at WOT? For now, I totally agree with mitzyman! If you're basically mostly cruising, get the 19" 3bld., if doing more tubing, & skiing, get the 18" 4 bld.

 

[Starcraft5834]

Chuck. you would be better off with a 4 blade over all......the 4 blade will improve hole shot, on plane easier and will maintain plane at lower speeds, better steering control around the dock.. the ONLY disadvantage is you will lose a mph or two of top end speed. No way around that... the choice is yours...

 

[steelespike]

Is 39 lightly loaded and what is the rpm at 39?

 

[jestor68]

His boat is listed as 4200 lbs dry.

Try putting that through the Mercury prop selector using a 1.62 gear ratio and see what you get.

39 actual mph using a 11% slip and his gear ratio/pitch works out to about 3600 rpm.

 

[chucksorce]

Thanks for the replies, 39mph was with myself only 180 lbs 60 gal of fuel 10 gal fresh water and I would say off my memory my tach was about 4300rpm, I should note that when I purchased the boat we went on sea trials and every time we went full throttle we would get a alarm from the boat. The alarm was a over rev condition due to a aftermarket prop, (I have no idea what pitch that prop was) the marina swapped the prop to the one I have now. As of right now I use the boat mostly for crusing but as my kids grow we will be tubing ect.

 

[chucksorce]

I would also like to add some advice I got from a local prop guy, he says stick with alum because stainless is not necessary for a lake he also said if I stay with a 3 blade drop the pitch I have by 4 numbers and if I go with a 4 blade drop number by 5, does this sound about right? I don't want to over rev the engine and what do you think about sticking with alum, I kind of had my eye on a Mercury Enertia prop because im kind of a speed freak and I want to give my boat every advantage I can get.

 

[chucksorce]

Sorry forum is not posting all my replies and I want to give you all the info I can, 39mph was with myself only 180lbs 60 gal of fuel and 10 gal frash water. I think the rpm was around 4200 and I use the boat mostly for crusing but that will change as my kids get older.

 

[SkiDad]

Unless I'm looking up the wrong info, you engine should be running between 4600 and 5000 rpm. For speed I'd be looking at a 19p. If it were my boat I'd be putting 17p 3 blade for water sports and watching my rpm.

I have mixed feeling about stainless - i have 1 of those and 2 aluminum props and I find my alum props run faster (but I'm sure it's just my boat) But your boat it would probably make a difference. regardless of what you pick I think you are going to pick up a speed or at least not loose any if you get you pitch down at least 2 pitch - you are not hitting your full HP at 4200 rpm.

 

[Maclin]

I know I have seen Volvo recommendation in their prop guides to go to stainless for 40+mph extended cruising speeds, less blade flex.

 

[chucksorce]

Once again thanks for the replies, so I went on the Mecrury site and now I think I may go with a Mercury spitfire 4 blade alum probably 18p possible 17p. What do you think?

 

[chucksorce]

Ok so now im thinking I will go with a Mercury Spit Fire 4 blade alum 17 or 18p, what do you think?