prop for 23' Sceptre

breadandbobbers · #1 07-22-2009, 10:34 PM

I posted this in general topic to, sorry for the double post but I need a new prop soon...I'm itching to get offshore.

I have a 1978 23' Sceptre. I had a Armstrong bracket installed on the boat recently and put a brand new 225 hp Opti on it. The prop before did well with the boat, a 14P Mercury Mirage. However now the propeller seems to not have enough pitch and gives too much bow rise--before the boat had the bracket the boat was definitely bow heavy and the propeller did well, not it does not. The boat maxes out at 6400-6500 rpms currently, and max rev on the opti is 6750

anyways does anyone have a similar setup or have any recomendations? I use the boat for fishing offshore so I am looking for something that will perform well in the open water.

eggsuckindog · #2 07-23-2009, 03:19 AM

Never heard of a 14" pitch prop - must be diameter - sounds like you need a bigger wheel but have to find out what you have in pitch now - I do think the Opti's are supposed to run under 6K though - the rev limiter may be 6750 but thats not recommended RPM - check the owners manual please

Fr. Frank · #3 07-23-2009, 02:48 PM

Quote:

....the rev limiter may be 6750 but thats not recommended RPM - check the owners manual please

2002 and newer V6 Optimax is supposed to be rev-limited to 6300 rpms. Above that it's supposed to cut out 2 cylinders to get it down. Rev limit on all the other Optimax motors is 6200. You can actually exceed the limit momentarily, but only for a few seconds before the limiter kicks in. My 90 Optimax actually limits out at about 6150, then an alarm goes off, and the limiter cuts out one cylinder intermittantly, and won't recommit to all cylinders until the throttle is retarded manually.

Bushwacker · #4 07-23-2009, 11:46 PM

Sounds like you might want to get that tach checked before doing any prop trials! Doesn't sound like computer will let it wind up that fast!

You might want to consider a 4 blade stern lifting prop. When I added bracket (and a new 427 lb motor), boat would NOT plane below about 18-20 mph with a 3 blade prop! With the old 300 lb motor hung on transom, I could easily plane at 12 mph. Now with a 4-blade prop, it will again plane at 12 mph no sweat, even with a very heavy load!

Fr. Frank · #5 07-24-2009, 12:59 AM

Bracketed motors tend to have more bow rise than transom motors. 6400 rpms is way too much for the 225 Optimax. I thought the factory rev limiter was supposed to cut in at 6300 rpms. Max rpm range for the 225 is 5000 - 5750 rpms, not 6750. Ask your dealer about that.

Since Mercury Marine doesn't list a 14" pitch Mirage Plus, I'm going to assume it was re-pitched down from a 16"P, which is the smallest I see in the catalog. If you're turning 6400, and want to get down to 5750 (max of max rpm range), I would estimate that you need an 18"P Mirage Plus prop.

(Posted in General thread on this topic as well)