Chris-Craft reprop

[210 Scorpion]

Hi all --

I have a 1984 Chris-Craft 210SL Scorpion. It has a 350/260hp MerCruiser, with the 1.5:1 drive. My current prop is a Michigan 31024, 14 1/2" x 17". It is in poor condition. My weight guess is somewhere in the 4300lb range with fuel

I'm looking to get a new prop this year, and hopefully go stainless. Some of the performance numbers from last year -- speed numbers are GPS.

1000RPM = ~5mph (spent some time there idling in and out of the marina)
3000-3100RPM = 29-30mph
4800-4900RPM = 47mph

WOT on the engine is supposed to be between 4400-4800RPM. Trimmed down it stayed in the 4400-4500 range, but when I trimmed it up some it picked up the extra speed and RPMs. Definitely runs better when trimmed.

I'd really like to be able to hit 50. But I also realize I'm on the Great Lakes, and rarely do I get the conditions to go wide open.. The boat gets used for tubing, cruising, beach hopping, etc. Its really an all purpose boat for me, especially with the cuddy.

Suggestions??

 

[Flysfloatsor]

Re: Chris-Craft reprop

Id stick with the same Pitch or maybe a 19. Ive had good luck with Mirage Plus props, and they are known for being fast. 50 is attainable.
Your boat is prob closer to 4000 lbs with fuel. I "think" its closer to 3300 lbs dry weight. I have the 1985 borcure with all the boats specs. They didnt change much from 84-85. Ill look tonight.

Post some pictures of it! Are you in ohio?

 

[1980Coronado]

Re: Chris-Craft reprop

It sounds to me like you've got the correct prop.....was your test done with a normal load or just you in the boat? It's normal to gain some rpm when you trim up to get the nose up and less boat in the water. If you are only slightly over max rpm when by yourself, it will come down a little when loaded with a few people. If you were normally loaded in your test then you might be able to increase pitch by 1" to bring the over rev down and gain some speed. If you switch from aluminum to SS, typically you drop down 1" in pitch to keep things the same. Aluminum flexes more than SS, so they drop the pitch by 1" to keep the rpm the same. You could try keeping the same pitch in SS....you may get a little more (couple mph) top end...you may not.