Need prop ideas for a pro craft 210cc has 200 promax with some jay smith mods

**Promax fishin** · 07-06-2017, 10:29 PM

Mostly setup for fishing boat seems to have pretty of power with a 23 pitch high five prop. Looking for a little more speed as I can get 57 mph at 5800 is all any suggestions? I did purchase a 22 pitch bravo 1 Lt but haven't tried it yet waiting for jay to finish motor up and then gonna see what happens.. With this prop give me more bow lift? Idk any help would be helpful. Thanks

**Merc 2.5** · 02-19-2018, 04:31 PM

I'm no expert on promax motors but they need more rpm than 5800 i believe. I think they say 6750 from factory

**Gordon02** · 02-19-2018, 09:40 PM

You'll get a lot of good advice, but it will come a lot quicker and be more accurate if you'll post some photos of the boat, jackplate used, and weight distribution. I own a 200 Promax also and have it propped to 6,500 rpm with a normal load.

What gearcase? What setback? What is the propshaft height? Do you use a trim gauge and do you know where parallel is on that gauge? The biggest mistake I see with high-speed set-up is wrong setback and wrong propshaft height for the boat and prop. Does the boat have a hydraulic jackplate? These details will help everyone weigh-in on set-up.

**Gordon02** · 02-19-2018, 09:46 PM

I'll add that a high-rake prop with a lot of grip/bite works well to hold the bow up with higher propshaft heights, but they can really hold the rpms down if they are buried. Props like the Trophy, Laser, even a Chopper are designed for high mounting and use with set-back leverage. That 5 Blade is more of a ski prop or one for heavier boats - it was not built for speed. There is too much developed blade area and sucks a lot of energy buried deep below the boat.

**Gordon02** · 02-19-2018, 10:32 PM

http://forum.allisonowners.net/index...book-pdf.8793/

This link will take you to the "Red Book" - a short, but insightful explanation of set-up terms and how to get there. This book is issued with every new Allison sold, but I find it very relative in theory to most pad-V hulls. Lots of Allison references since it is the Allison Owners guide, but it covers the mechanics of speed, lift, setback, height, and trim very well. I hope you find it helpful.

**David** · 02-22-2018, 08:49 PM

Do you need more bow lift? How much trim do you use?

cheap option for me is used Trophies
my expensive choice is to call Hydromotive

**NeedOne** · 02-25-2018, 01:31 PM

What would be considered buried for a trophy?
Say as a reference, 2-1/2 below pad with 10 in setback

**Gordon02** · 02-25-2018, 07:39 PM

2 1/2" below the pad could in theory have 3~4" of the blades of a Trophy surfacing on a boat running 70+ mph, but still be buried at 50 mph. Speed is relative, but 2-1/2" does not sound like a buried prop height. What I've learned with the several V-hulls I've owned is that's it is pretty easy to get a boat to run at 90% of it's full speed potential. Getting that last 10% is a science and takes perfect front-to-rear balance, a propshaft height and trim angle that will apply near 100% of the thrust to forward movement, and a hull angle of attack of a quoted "4 degrees positive to the water's surface". The before mentioned link of the Allison Red Book is a great read.
Water is 814 times more dense than air. If your boat is going to go fast, it needs to "fly" above as much water as it can. The propshaft would be level with the water's surface, the hull's pad attacking the surface at that 4 degrees for lift, and no excess trim. Over-trim is one of the most common miss-uses of hydrodynamics I've seen through the years - too much trim pushes the stern/rear downward and increases wetted surface, increases the angle of attack, and miss-places the thrust downward instead of all forward motion. This is common on boats with motors that are mounted too high or don't have enough set-back to lift the boat without excess trim. I was one of those offenders.....for years I over-used trim to lift the bow only to push the stearn down, making the wetted surface far worse that it could be. Had I used the right amount of setback, higher propshaft settings, and high-rake, high-lift props - the boat would have reached something closer to that full capacity.

I don't want to sound a know-it-all, I still have lots to learn. But I will say this - buy and set-up an Allison to run in it's top 10% and you learn what "feels right" and when it's mid-90's on the GPS, you know you're close. The book helped me understand a lot. Gordon