What style prop do we like on a 20' Sceptre

Basketcase · #1 07-26-2018, 11:17 AM

Its time for a prop. This one is old, dinged up, and just tired. I want a new shiny stainless one. I'll keep this as a back up to get me home in a situation.

My setup is a 77 20' Sceptre with 2005 Optimax 175 on the transom. Its a 19pitch aluminum prop. RPMS seem fine. Cruising at 38mph at 5k rpms with more to go. I've adjusted motor height to where it should be. Plate visible at cruise.

The question is do we like 4 blade or 3 blade props for this boat? I know the typical ins and outs of a 4 blade vs 3, but I thought maybe there were more things to consider when its on a Sceptre, due to its different weight setup.

What I do notice now is it blows out easy in tight turns, or even when trying to accelerate after a quick drop off plane. But mostly turns. I don't think it was like that until I brought it up 2 holes. The plate was well below the water on plane before though.

The use of the boat is as a utility to carry stuff to and from the island house. We also fish a lot in the bay, and probably will venture out a bit to open water, but rarely. The bay can get ugly so a slow plane speed would be preferred. Obviously I have a 175 so I want to go fast too!

Suggestions?

caper · #2 07-26-2018, 11:55 AM

Drop it one hole and stay with a three blade.

kmoose · #3 07-26-2018, 12:42 PM

Leave the motor where it is as a new stainless prop will have better cupping and grip. I would choose a Mercury prop. They make some of the best props on the market and are used on all manufacturers.

If you are going with a 4 blade, I would go with either a 17 pitch Rev 4 or Vensura

Most big mercury dealers have loners or will let you try a prop. You can also contact Ken @ prop gods and get good advice.

Fr. Frank · #4 07-26-2018, 03:12 PM

Quote:

Originally Posted by kmoose

Leave the motor where it is ...go with either a 17 pitch Rev 4 or Vensura

Most big mercury dealers have loners or will let you try a prop.

For handling and utility absolutely try the 4-blade first. Drop 2-3 inches of pitch from current 3-blade. For the Opti I suggest the Rev4. You may still have to drop the motor one hole, but I'd try the 4-blade with it's increased stern-lift first.

Basketcase · #5 07-26-2018, 04:14 PM

Good info. I'll be stopping in to the dealer tomorrow to see if they have a Rev4 in 17p for me. I'll report back once I get to try it out. Plus I'll have my Smartcraft tach so I can really see if I'm at the right RPM too.

FLexpat · #6 07-26-2018, 05:27 PM

A couple of years ago I talked to Ken at Propgods about blowout on tight turns when the drive is high - If I remember correctly, he said that a little bit of cup on the tips will fix it without having to change height.

Capt Terry · #7 07-26-2018, 07:23 PM

When I picked up my new Seafari in 1976 from Brown & Hauptner, Mark Hauptner who had raced for Moesly added a cup to my Merc prop. Not sure how common cupping was at the time. Didn’t find out until I met Carla a few years ago that Frank Brown was Moesly’s race mechanic. Explains why my SeaCraft was set up so well!