Prop Help for Maxum

I'm interested in a new propeller but am not certain what to get. I have bought a used 1989 Maxum 2050SR (19'7" with a 7'4" beam) with a Mercrusier 5.0L/LX (pre-EFI) at 230Hp and an Alpha One outdrive from the original owner, she's been kept in fantastic condition and looks/acts like new in almost every regard but I am still interested in obtaining the maximum performance from her.

According to the manual the WOT for this engine should be about 4200-4600RPM. Currently she has a 23P stainless prop of unknown model.  I also have what MAY be the original aluminum prop with the numbers "48 78122 A40L 21P" stamped into it. I don't know the diameter of either prop but they both look to be about 13 and 13.5 inches diameter. Both of those props are 3 blade models.

At WOT this boat is running between 48 and 51mph across the water and about 4300-4400 RPM so right close to the middle of what should be the boats best WOT RPM according to the manual.

Shortly after buying the boat I added a "SE Sport 300" Hydrofoil and a performance trim tab.

I'm fairly happy with the top speed (though am one of those people who believe the faster the better) and it does appear to be in the RPM range at WOT that it should be, but a local pro skier/wakeboarder today was on the lake and we got to talking and I told him I came out to check my take off power to see if it felt better/came up faster after having added the hydrofoil because I had concerns about pulling up skiers as the boat seemed to feel a little slow on the hole shot.  So he switched his line to my boat and we tried it (skiing, not wakeboarding) and though he came up on the first try he said later that he was having to kinda pull himself up a bit more than he should and the boat was a little slow on the take off.  This was with only one skier and the boat lightly loaded. I haven't yet put in even my anchor, ropes, skis, towables, or any of the other junk we tend to carry during the summer, and no other passengers (I normally have 4-6 people with me).

I would like to improve the hole shot enough to reliably pull up one skier and we were really hoping to be able to pull two at once next summer. But at the same time I hate to lose our top end very much, especially when it seems to be so close to where it should be under WOT, though I had not tried it yet to see if it's still in that range when the boat is fully loaded.

I know some of the stainless props have progressive pitch giving you a better compromise, I don't know if the one on it now has progressive pitch or not but do know that it appears to be slightly warped which may also be affecting performance. I'm confused as to what I need to be looking for. Is there a way I can keep my top speed and keep my boat in the proper WOT range while getting a much better hole shot?

Suggestions please??

Thanks in Advance,
James K. Hastings
Greer's Ferry Lake, Arkansas

 

James,

In all of my experience, and for the uses that you describe, buy a 23 high five. It will give you the best OVERALL performance that you are chasing. Any other prop will always have a compromise somewhere. The Hi Five will be a mile or 2 an hour short on top, but will shine everywhere else.

Randy

 

 

Please submit whatever questions you have to IHRTechTalk@yahoo.com.  All questions and answers selected will be displayed on this page as they come in.  Note: though all boaters are welcome, priority may be given to I.H.R. members.  Randy can not be held responsible for any advice given.  Though his information and expertise is second to none, he has no control over what you do with your boat.  It is up to you to boat safely and act responsibly, and his advice is only to be used as a guidance for your high performance boat/motor of which you are the one responsible for the risks involved.

Thanks,
Mark C.

 

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