Guests - If You want access to member only forums on HSO. You will gain access only when you sign-in or Sign-Up on HotSpotOutdoors.

It's easy - LOOK UPPER right menu.

Sign in to follow this  
Followers 0
snoozebutton

Do I have the right prop on my boat?

7 posts in this topic

What I have on came from the manufacturer. It's a 90 hp 4 stroke Johnson and on the prop it has 3X14X17. I'm guessing this mean 3 blade, 14 inch diameter, 17 pitch. It's seems good out of the hole, a little disappointed in the top end (38 mph with just me), and I'm getting some porpoising. I'm running 5,800 RPM's WOT and the manufacturer recommends 5,500 RPMs at WOT.

Would I get more porpoising with a 19 pitch? I think a 19 would give me a better top end at lower RPMs wouldn't it?

Appreciate any advice!!!

Share this post


Link to post
Share on other sites

The 19 would get you more top end and lower rpms ---- also less hole shot.

I don't know about the porpoising - I wouldn't think you'd get more. Redistributing the weight in the boat might help. Also a stainless prop might take care of the porpoising by giving you more stern lift, it's one of those things where you'd have to try some props to see what works best. It's always a trade-off, every time you gain something in one area you're going to be giving up something else in a different area.

Share this post


Link to post
Share on other sites

I would try a 19 pitch 4-blade stainless renegade prop. That should keep your holeshot up to par, and also give you better top end whle eliminating most of your porpoising problems. For each pitch you to up, typically you drop about 200rmps. I would guess it should also bring down your rpms close to 5400. The only other solution to your porposing problem (besides prop) is to change the engine height or go with an ugly whale tail. You will also like a stainless 4-blade much better if you have any blow-out problems on tight turns, or if you like to pull any skiiers or tubes.

Share this post


Link to post
Share on other sites

The 14" diameter sounds a little large to me. I'm running a13 1/4" x 20 stainless prop on a 130 Yamaha. If your running an aluminum prop I would recommend going with a stainless 17P 3-blade prop. The stainless prop is more aggresive than the aluminum prop due to the cupping and rake and should lower your rpm some while at the same time maintaining good holeshot and top speed. A 19P 4 blade stainless prop will be too much prop IMO. 4 blade props of the same pitch tend to reduce rpm a couple hundred rpm over an identical 3 blade. My $.02.

Share this post


Link to post
Share on other sites

what do you expect out of a 90 horse power that sounds good to me.

Share this post


Link to post
Share on other sites

I have a 75hp mariner and use a 13/19 and a 13/21t the 19 gets me going on plane faster than the 21t. but the 21t gets me a few more miles and hour both gat me to the buzzer @ 5500 rpms these props are not stainless. 1 have a 17ft lund Mr. Pike.I have got it to 41 by myself with the 21t and getter to go 38 with the 19. my buddy tried stainless on his 75 and only gained two miles and hour with the same pitch, he also tried a 13/17 and that thing freakin rocked just no top end it jumped out the hole really good tho.

Depends on how far you travel on water I only use the 21t up north and millac.

Share this post


Link to post
Share on other sites

Thanks for all the replies. I'm going to head to the dealer this week and talk it over with them but now I have some info so I won't sound like a total one-who-thinks-I-am-silly. grin

what do you expect out of a 90 horse power that sounds good to me.

I said a "little" disappointed. Just thought that with a 16' Alumacraft I'd be getting a little over 40 with that motor which I still think is possible with the right prop but first I have to deal with the porpoising issue.

Share this post


Link to post
Share on other sites
Guest
This topic is now closed to further replies.
Sign in to follow this  
Followers 0



  • Posts

    • I have been going to golden meadows lately to work my dog so far we have shot 24 birds over him. One more time at the preserve before the season starts and we are itching to get out in the real fields!  
    • Wow do the unicorns fly in your fantasy too?
    • Would you like me to put sugar in your medicine to make it taste better?
    • Unless: If no candidate wins an absolute majority in the Electoral College, the election is decided by the House of Representatives. Thus, if Johnson were to win, say, Colorado while Trump and Clinton split all other electoral votes 50-50, the House would pick the winner. Given that Trump and Clinton are the most unpopular candidates in recent history, a divided House might compromise by selecting Johnson, a former two-term (Republican) governor of New Mexico.
    • It's probably going to be late this year. I got my itch scratched at Traxlers reserve in LeCenter today at least so that helps but really for me the pheasant season doesn't get into high gear until after deer season. Normally the first few weeks are too warm to be out a whole day with the dogs and there are too many corn fields in. By the 3rd week in November the temps have dropped and the corn is mostly out and that's when it gets better and of course first snow...... I am fairly optimistic about the bird populations this year. Obviously the rain we had was a wildcard and it's hard to say right now how that has impacted populations but there was a good group of birds that carried over from last season and the winter didn't take too many.
    • You sound like Dingle when someone spells isn't without the apostrophe.  It's like he can't even comprehend the sentence.
    • I'm saying that the people get what they deserve and that includes us, you all and me too.  As one of the characters in catch-22 said.. "They can do anything you can't stop them from doing".   And we have allowed the Clintons, a pair of crooks from the git go, to gain control of the Democratic Party, with a brief hiccup from Obama who only got to congress by getting a machine judge to release his opponent's sealed divorce records.  And we allowed the Republicans to leave in place a setup that encouraged every doofus that could rub two nickels together to get in the race.   Michelle Bachman?  Rick Santorum?  Rand Paul?   and of course Donald Trump....   Throw ten or 20 of them on TV about 50 times and see what happens.  And we all mostly just ignored it so the celebrity with the media skills got the nod, because he articulated the rage and disgust of a significant part of the voters, and he didn't have to rely on contributions to campaign.     Now we are being told, in the words of La governor Edwards supporters.."Vote for the Crook.  It's important." So, yes we deserve what we got.  Now the decision is which of these two will do the least long term damage to the country.   Maybe Jill Stein or Gary Johnson would but it ain't gonna happen, and anyway they would be jesse'd (term invented by me) by the congress like Jesse Ventura was by the state legislature after the first term since Jill and Gary have no power base.  
    • You and your back slappers bring up stuff Trump did or said in 1850...are you kidding me.   #hypocritesandfrauds
    • It sounds like you are describing a transmission slip in first gear? how many miles on it? Is the check engine light on? Have you checked the transmission fluid level and condition?
  • Our Sponsors