Went to try this out. Could not answer the question about boat specifications. Spec sheets don't give the specifics. 2008 Ware Eagle Predator 861. Anybody know? What prop I need?
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Went to try this out. Could not answer the question about boat specifications. Spec sheets don't give the specifics. 2008 Ware Eagle Predator 861. Anybody know? What prop I need?
What size and brand is motor?? How long is the boat/weight?? Is it a semi vee or flat?? What is on it now?? RPM?? Speed?? How is holeshot?? I really like to have a base run for figuring a prop. To see real world stuff...most of the calculators are just giving you a base anyways. What is the RPM range of motor and what is your WOT rpm with an average load?? Lightly loaded...you, gas, and boat stuff (trolling and electronics) you should be at the upper end of the rpm range. If you are there and you like your hole shot leave it alone. The more info you have the better we can do at figuring out what prop.
Quote:
Originally Posted by Scrapper
only specs is length and deadrise on their web.
War Eagle Boats - Boats - Predator - 861 Predator
Have a 90 Yamaha 4 stroke. Prob put a 115 Yamaha 4 stroke on it.
I can't figure without figures???
I would contact wareagle on that without any baseline figures. They will tell you what prop to run. After you get the prop you can run it and we can go from there. Alot of places will let you test a prop. Our shop here in Nashville has some used props for testing purposes. Mercury actually has a testing program...they send you a prop...you test it...you send it back...they send you another to try.
I would really try to find someone that has a prop and try some different pitches. I am going to venture out and say around a 21" pitch will be close. I do not know how torquey the 4strokes are...I also do not know what diameter prop the yammie 4strokes are...I would figure same as the 2stroke lower unit...I will check and see though.
I like a fourblade myself. You will have alot of benefits over a three blade. Many say it will slow you down by a couple mph...but the newer designs you really do not loose to much. You will have better holeshot...more control...more stability...more bite in rough waters...just better all around drivability. I'll do some research and let you know what i find out
Okay, I've got this info so far...
Both engines rpm rated at 5000-6000rpm I would run light loaded 5700-5900wot...average load 5500-5600 wot would be good...just my opinion...I would ask yamaha or the dealer you are working with.
90hp has a 2.31 final gear ratio
115hp has a 2.15 final gear ratio
I would think with the lower ratio of the 90hp you will probably get about the same rpm with the same prop...just a slower speed out of the 90...just a guess.
The following link goes to the yamaha website and shows all the props that yammie makes for those engines...says they have the "small hub"
http://www.yamaha-motor.com/outboard...mall%20Hub.pdf
I did read on another page that someone bought the same boat with a 115 4stroke on it and the dealer put a 4blade 21" on it...they claimed it should run 50mph.
The yammies will also take merc props. If you find that a 21" will work for you...I would look at a 21" trophy plus from Merc. The trophy "plus" will the PVS system and allow you to fine tune slippage for a better holeshot. The regular trophy just has holes in it so you can't tune it. This is an over hub designed prop so slippage can be a problem in some cases. You can have a 15 dollor weed ring put on it and then all the exhaust will be ported through the PVS holes so you can tune it to your liking. These will allow the prop to slip due to exhaust going over the blades...almost like slipping a clutch to take off...lets the engine build up rpm...then as the prop speeds up, these holes get sealed off from the water rushing by them and the vaccum created from your foward thrust helps to pull the exhaust through the center of the prop. Just some thoughts. The yammie props are all even numbered pithchs so you'll go from a 20 to a 22" pitch.
Each inch of change in prop pitch will change your rpm usually by 200rpm. So when you get your baseline, and know your target rpm you can play with your props. Say a 21" is running at 5500...the same prop in a 19" should run around 5700 with the same load and vice versa. Hope this helps some.