Prop Advice

[240ES 0]

Hi, First time posting and I'm looking for a little propeller advice. So I have a year 2000 240 Explorer Sport in fantastic condition that I purchased in July 2013. I think i need new prop??. My engine is a Merc 5.7l with AlphaOne drive. ~300 hours on engine. Guessing 260-280 HP on that.

 

Here's what I know.... My WOT is only 3680 rpm on smooth water trimmed well and the recommended range is 4400-4800 rpm and at my WOT I'm only getting 30-32 mph. Granted that is with a "loaded boat" so dry weight 4200 + fuel + gear + 2 people = ~5000#. I currently have a 3 blade aluminum prop with 19 pitch which is a little scratched (no dents) but not bad.

Questions:

1) should I be getting more RPM's out of my boat? I'm 700 rpm below the low end of the range.

2) should I expect more speed ? or is 32mph under conditions above about as good as I can expect?

3) should I expect better performance from another prop?

4) If so, any recommendations on prop size/pitch/blades?

 

Thanks in advance!

 

Jay

[GetAway 0]

Check your tuneup, timing. I was getting 4800 rpm until I had a shop 'tune' my engine. They didn't tune it up while in the water, they used muffs on the hard. I lost 800 rpm. I use to be able to get 43 to 45 mph but now I can only get 4000 rpm and 35 mph.

 

I'm going to check my timing and retune the engine myself and the boat will be in the water when I do. I have the Volvo 5.7l GS engine which I think is close to your engine, both are 350's.

 

This might be your case too. Your rpm's seem to be pretty low. Look on this site for an owner's manual for your boat, they have several on this site. That might help you out. Also search the web for your engine and any information you can find on the specs of your engine and the rpm range it should run at.