stainless prop question

[Deas]

Was running an alum 13.5x19P prop on '98 Merc90 w/16ft K&C fiberglass boat, but it cracked and a big chunk fell off. Ran WOT 4800rpm or 5000 when trimmed way up (37-40mph). Looking at props on ebay now, what differences would a stainless prop give in terms of performance, and what size recommendations...Cheers and Thanks in advance

 

[emckelvy]

Re: stainless prop question

A stainless prop of similar design and same pitch would typically give you a better hole shot and will have a bit more rpm in the top end, so might be faster.<br /><br />Props are so variable though, that it's hard to generalize.<br /><br />One thing about the Big 3-cyl's is that they don't like to rev beyond the recommended rpm range, so don't get a prop that will ovverev the motor.<br /><br />If you stay within a pitch-size of your current prop, you should find something that'll work well for you. <br /><br />For example, a 20" stainless would likely do well on this motor. A 21" depending on the design would probably work too. <br /><br />But don't go with less pitch than your current prop, guarantee it'll rev up too much.<br /><br />HTH...........ed

 

[Deas]

Re: stainless prop question

Thanks Ed thats good information. Another question, what differences would I see between 3, 4, and 5 blade props. <br /><br />also, do some props require a hub kit? Is that something I would get so it would slide onto my propshaft.<br /><br />Thanks again...

 

[timmathis]

Re: stainless prop question

It will take A prop shop to install A new hub. $60-$70 Job.

 

[XcellR8]

Re: stainless prop question

Originally posted by Deas:<br /> Was running an alum 13.5x19P prop on '98 Merc90 w/16ft K&C fiberglass boat, but it cracked and a big chunk fell off. Ran WOT 4800rpm or 5000 when trimmed way up (37-40mph). Looking at props on ebay now, what differences would a stainless prop give in terms of performance, and what size recommendations...Cheers and Thanks in advance

I'm in a similiar situation (wondering what prop to go with). I just bought a 15 1/2' FG open bow with a 91 90 hp Merc and the prop it came with is a 13 3/4" x 21P Trophy Plus SS 4-blade. I've only had the boat out a couple times but it's running around 38 mph @ 4400 rpms. I'm thinking I have to go down to a 19 pitch or possible a 17.

 

[emckelvy]

Re: stainless prop question

If you're only getting 4400 at Wide Open Throttle I'd expect that's too low. Look at the mfr's recommended rpm range for your motor, and lightly loaded it should be towards the higher end of that range. Going down 2" in pitch will probably add about 200 rpm to your top end.<br /><br />Regarding the prop hub question, what is being asked is about some of the newer-design props that do not have integral hubs. They do indeed need a 'hub kit' that is usually purchased separately. I guess the advantage of these is that you can buy several prop bodies of different pitches, and only one hub kit. Plus the parts of the hub are easily replaced if worn out.<br /><br />A 4-blade prop will be smoother than a 3-blade and will also hold better in turns (more resistant to ventilation due to more blades being in the water at any given time).<br /><br />More blades may or may not be slower than a 3-blade, a lot depends on the prop design.<br /><br />The Merc High Five prop is Da Bomb but Man! are they expensive and you probably won't see a lot of benefit at your HP and performance level.<br /><br />BTW Comprop et al of the composite-type of props makes a pretty good 4-blader that is quite inexpensive too, in some pitch ranges (17" and 19") that might work for you.<br /><br />HTH......ed

 

[XcellR8]

Re: stainless prop question

Originally posted by Ed Mc.:<br /> If you're only getting 4400 at Wide Open Throttle I'd expect that's too low. Look at the mfr's recommended rpm range for your motor, and lightly loaded it should be towards the higher end of that range. Going down 2" in pitch will probably add about 200 rpm to your top end.<br /><br />Regarding the prop hub question, what is being asked is about some of the newer-design props that do not have integral hubs. They do indeed need a 'hub kit' that is usually purchased separately. I guess the advantage of these is that you can buy several prop bodies of different pitches, and only one hub kit. Plus the parts of the hub are easily replaced if worn out.<br /><br />A 4-blade prop will be smoother than a 3-blade and will also hold better in turns (more resistant to ventilation due to more blades being in the water at any given time).<br /><br />More blades may or may not be slower than a 3-blade, a lot depends on the prop design.<br /><br />The Merc High Five prop is Da Bomb but Man! are they expensive and you probably won't see a lot of benefit at your HP and performance level.<br /><br />BTW Comprop et al of the composite-type of props makes a pretty good 4-blader that is quite inexpensive too, in some pitch ranges (17" and 19") that might work for you.<br /><br />HTH......ed

The specs I've found say 5000 to 5500 rpm. The dealers I talked to say around 5400 so that's what I'm going to shoot for.

 

[bluewater19]

Re: stainless prop question

Deas,<br /> Try looking on ebay for a 18 pictch merc vengeance prop. This is a good stock style stainless replacement for your busted 19 pitch aluminium prop. You won't be able to find a highfive for your motor because the lowest pitch merc makes for the small gearcase is a 20 pitch. Same with the laserII.<br /> <br /> If you can find a 4 bladed trophy plus in a 17 pitch that would fit your motor, it will bring your rpm up a little closer to the 5500rpm redline.<br /><br /> Check out theses auctions.<br /> http://cgi.ebay.com/ebaymotors/MERC...ryZ26456QQssPageNameZWDVWQQrdZ1QQcmdZViewItem <br /><br /> http://cgi.ebay.com/ebaymotors/Merc...ryZ26451QQssPageNameZWDVWQQrdZ1QQcmdZViewItem <br /><br /><br /> <br />I have no connection to the sellers bla bla bla,<br />just tring to help a fellow Iboater out.<br /> <br /> I have 1996 merc 75 and know that finding the right prop for these motors is alot harder than finding one for a big gearcase motor.<br />Good luck!

 

[Deas]

Re: stainless prop question

Thanks guys... <br /><br />

You won't be able to find a highfive for your motor because the lowest pitch merc makes for the small gearcase is a 20 pitch. Same with the laserII.<br />

Bluewater just to clarify here are you saying the propshafts are different sizes btw 90HPs and larger motors and not all props will fit? Would hub kits be available that would fit?<br />I am looking at a 13.5x17 pitch high-five for sale.

 

[Stinger313]

Re: stainless prop question

SS prop wont flex at high rpm like alum will. SS will give you better topend but the down side is if you hit anything the SS will not give and you will likely break something internal.Same pitch shound be ok,whatever you choose to use.

 

[sangerwaker]

Re: stainless prop question

The 17 high five will NOT fit your motor. Merc has two different sized gear cases. The diameter of the hubs on the props are different sizes. On high fives, odd pitch are large gear case (135 hp and up or 4-3/4"), even pitches are the small gear case (4-1/4").

 

[bluewater19]

Re: stainless prop question

Thanks sanger,<br />Thats what I was going to say.

 

[Boatin Bob]

Re: stainless prop question

There is a high 5 on ebay right now in Canada. It's a 13 x 22 asking $225 US, this thing retails for around $900 here in Canada I was seriously thinking about bidding for 115 Merc. Looks to be practically new. Not sure how much this might pull down your WOT RPM's though. High 5 on ebay

 

[bluewater19]

Re: stainless prop question

Boatin bob,<br />What prop and WOT rpm are making now??<br />If you already use a 22 pitch you will be fine. expect around a 300 rpm drop with that prop per 2" of pitch.

 

[Deas]

Re: stainless prop question

Thanks guys got a pretty clear understanding of what the options are now and what I need. Will post some followup results when I try on some new props.<br /><br />A couple more notes I have come across that will help guys starting a prop search:<br /><br />Of incredible value is the mercury parts express website, in there is a spreadsheet that shows all the props available for 3-4 cyl mercs (and probably for others), and lists the prop sizes, blade numbers, serial numbers, and manufacturer so you dont end up spending cash on a prop that wont fit your model.<br /><br />Also found the mercruiserparts website very useful to punch in the serial number and compare the prices it lists with those offered in other places...<br /><br />Cheers...

 

[sprinkler]

Re: stainless prop question

While a stainless steel prop may be more stiff and less likely to break, that also means that if you hit something in the water the energy is transferred to your lower unit, possibly causing damage. I'm a lake boater myself, but if you do a lot of river boating you may want to consider that (lots of stuff in the water).

 

[Boatin Bob]

Re: stainless prop question

bluewater19...thanks. I was thinking the same thing. I currently have a 2003 115 hp 2+2. Running an aluminum 13x19 with WOT of 5300. Wasn't sure how much WOT RPM I would lose going from a 3 blade alum to 5 blade SS. I can afford to lose some top end but the bottom end might be better as the boat is mostly used for skiing and wakeboardingf.