Prop size for 1997 225 Penn Yan outrage. 4.3 mercruiser

[Bad Habit]

I have a 1997 225 Penn Yann Outrage with a 4.3LXH GEN+ Merc. I'm looking for the correct prop size for this motor. Right now, I'm only getting 3900 RPM at WOT. I cant read the numbers on the numbers on the prop that is on now. Also, should I stick with a 3-blade or go to a 4-blade.? The boat is used primarily for trolling. Any help would be appreciated.

 

 

[sherman brown]

on my 21' cobia I ended up with a 17p high five on it. but the same pitch in a 4-blade should work great for you. I would check on eBay for a used Revolution 4 blade 17p. what is the max RPMs for that motor? I

would think around 4800 and if so you are running really low. how does it get on plane and what speed are you getting now?

[rolmops]

I would start with checking the timing and make sure that it is properly set. That could easily bring up the rpm and save fuel.

If it is only trolling you want you should go down considerably so you can troll slowly at a slightly higher rpm Three or four blade props have more to do with hole shot and little to do with trolling

Your boat size would commonly have the 14 diameter X 19 pitch size prop, maybe 21 but that is less common. Every number you go up or down makes a difference of about 200 rpm, so if you go from 14x19 to 14 x16 you would bring up your rpm roughly 600 up. In your case from 3900 to 4500. That is.. according to calculations on paper, but boats do not know how to read so you should take that as an approximate specially since those calculations are based on maximum speed/ rpm  when the boat is on plane. But still ,it would be your best rule of fist.

Edited February 3 by rolmops

[Bad Habit]

 Thanks for the info. It looks like Max rpm should be 4400-4800. I'm getting about 3900 with a top speed of around 34 MPH. With 6 people on board it fights to get up on plane. It also has a Fin on the lower unit to help it get on plane. I'll have to try to figure out what's on it now.

[Mike M]

I also have a 97 Pen Yan 225 Outrage. Bought it from a guy in Sanduski back in 2012. He had the wrong prop on it and didn't know it. I was suspicious it was wrong prop even though i'm no expert. It was a S.S. prop with wrong pitch. I hate SS props. Anyhow we have a prop shop in Buffalo area called Pier Prop. They let me try a couple aluminun props they thought would improve performance. They were right. My boat is in storage right now at friends barn. I'll get over there and get prop specs and get back to you. BTW someone said WOT should be 4400 to 4800 rpm for that 4.6 motor. Without looking it up that does sound right.

[sherman brown]

13 hours ago, Bad Habit said:

 Thanks for the info. It looks like Max rpm should be 4400-4800. I'm getting about 3900 with a top speed of around 34 MPH. With 6 people on board it fights to get up on plane. It also has a Fin on the lower unit to help it get on plane. I'll have to try to figure out what's on it now.

your speed isn't that bad but you need a lower pitch to improve hole shot. but most times going to a lower pitch might hurt your top end a little. but it's a fair trade-off to get a better hole shot and get your RPMs up a little. and just so you know going to a 4 blade should improve your hole shot. my boat started with a 19p 3 blade that struggled to get on plane. so I got on eBay and bought a 19p high five that jumped my boat up on plane. it was like I had bought a new boat. but my RPMs were low so I tried a 17p high five and everything was perfect. with the 19p it took forever to get up and now it starts getting up as soon as I hit the throttle.

[Bozeman Bob]

Fin on lower unit is supposedly designed to keep your boat on a plane at a lower speed . Not to help you get on plane . I don't believe in them ,especially for the size of your boat . If they were the " answer " they would of been integrated into all lower units decades ago . I would pull that off , nothing but drag in your case .  Lowering your pitch will NOT negatively affect your top speed , should increase it . Do the math , 21 " prop  X 3800 rpm will get you how many inches you traveled ( no prop slip figured in )  Now multiply 19" X 4600 rpms . Not having your exact numbers ,just using this as a example.  Your engine is constantly lugging ( wearing out the engine ) right now , know matter the speed and burning more fuel in the process . SS props will be a tad more efficient as the blades don't flex like aluminum will , so less prop slip . Drawback is , you hit something at cruising speed and the prop shaft takes the brunt of the hit , vs the " give " in aluminum.  4 blade will have less slip , smidgen less top end ( drag of extra blade ) and slightly lift the stern of the boat . Probably your best bet if you're constantly leaving port with a full load . 

[Bad Habit]

 Thanks all for the replies. I never believed in the fin either. It was on the boat when I bought it 2 years ago, so I figured someone knew more than I did. When I re-prop I'll probably take it off. I found the spare prop that came with the boat, and it is a 21 pitch so I'm thinking that's probably what is on it now.

[Mike M]

Bad Habit- Went to visit my 225 Outrage in barn today. Prop on it is 14.5 x 19P. Bought from Pier Prop in Tonawanda NY 716-875-1777 back in 2013.  Been very happy with hole shot and WOT is in that 4400-4800rpm range. I believe its a Michigan Wheel prop and its aluminun. Like i said i don't like SS props had bad experience years ago. Hope this helps.

[Bad Habit]

 Thanks Mike. Just curious, Is it a 3 blade? 

[rolmops]

Just bear in mind, that the bottom condition of the hull plays a big role. another factor is overall weight of the boat. What works for mike may not work for you at all.

What Mike did say about going to a place like pier prop is very valuable. The people that give you a test prop to run can save you a lot of money. Instead of spending money for a prop that does not fit the bill and then having to buy another one (very often there is no return on props even if only used for a few minutes). You may have to pay more than buying online, but you get the right one the first time around. I should know. Every time I step into my shed I see a thousand dollars of props that just did not fit the bill.

Edited February 5 by rolmops

[Mike M]

Yes its a 3 blade. Also a mistake in previous post motor is 4.3 liter. Good luck.

[sherman brown]

9 hours ago, Mike M said:

Bad Habit- Went to visit my 225 Outrage in barn today. Prop on it is 14.5 x 19P. Bought from Pier Prop in Tonawanda NY 716-875-1777 back in 2013.  Been very happy with hole shot and WOT is in that 4400-4800rpm range. I believe its a Michigan Wheel prop and its aluminun. Like i said i don't like SS props had bad experience years ago. Hope this helps.

just to add to your post. if you decide to go with a 4-blade prop it is recommended to drop 2" in pitch over a 3-blade prop. I highly recommend switching to a 4-blade for better everything, better handling in rough water or in turns, and better lift, the only downside is if you have a 3-blade of the right and the RPMs are right then going to a 4-blade might cost you 1 or 2 MPH at WOT. but in your case going to a 17p 4-blade prop should improve everything. and I will always use a high-five prop on any 8-cylinder Mercruiser that I get.

 

now my son and I went together and bought a 26' Sylvan glass boat that has an elephant ear 16p prop that is on the boat. but if he will let me i still want to just try my 17p high-five prop just to see which one performs the best.

 

and I don't know what motor you are running to get those numbers with a 19p aluminum prop. but he is running the 4.3 6-cylinder motor.

[Shakemsam]

I went to a 4 blade and ha a bit higher rpm and more control at low speeds including trolling.