Which Prop?

[Hazardace]

Hi All,
I'm new to the group for a few weeks. I have been lurking through the posts. Seems like a lot of good info here. Anyway here is my dilemma. I have a Bennington 2575GE Pontoon with a Merc 115 4 stroke on it. I just bought it at the end of last year so, I haven't messed with it a whole lot. My previous boat was a Suntracker fishinBarge 21 which i equipped with a pontoon prop. It made a big difference. Anyway, The prop that came on the motor I am unhappy with. its a Michigan vortex 13.75X15. Boat runs about 22. Now I realize its a bigger heavier boat but, It should run a little better than that. It seems not too bad out of the hole but from like 4000 to 6000 there is nothing there but slippage. I think the bigger ears on the pontoon prop would make a big difference. I was wondering if anyone tried the merc black max pontoon props? Im looking at the 48-77338CP1 which is a 14X11 with extra cup. Same prop with different pitch is 48-77340cp1. Thats a 14x13 ex cup. Now I ran the prop selector on the merc marine website and came up with a few different choices. The motor test on BH bulletin used a 48-7738A45 which is a 14X11 pontoon prop no exta cup. That was tested on a 24 foot Bentley with a 115 2 stroke but same difference sort of. Boat ran 29 mph. Has anyone messed with the different props Ex cup versus just plain pontoon prop? And any suggestions on which one to get? Wish I could try them all out but, Im gonna have to make my best estimate guess. So, I guess what I need is the 11 pitch or the 13 versus the excup or not. Any feedback or input would be greatly appreciated. Thanks.
PS. Bear with me I have no signature or pictures yet. Soon to follow. Thanks.

[limulus]

I have a Bentley 240 with a Merc 115 4s. The best prop I ever had was a Solas 14x11. I got 24MPH with that one until I hit a submerged log and broke it. I now have a Black Max 14x13 and before I put a Pontoon Water Glide on, it ran 23MPH. I have a Turning Point Hustler 13.75x15 that I'm going to put on now since I have the Water Glide.

There is something about the gearing in the Merc 115 4s that just does not work well with a pontoon. I know there are guys with 90HP Merc 4s motors that run faster speed than me. My motor is a 2007 and I believe that the 2006 motors were a little different. I have also read that the new 115 4s Mercs have a better gear ratio (2.33:1). If I could find a dealer that would install the new gear I'd consider it.

[Robbins911]

Hello All,

I'm new to this forum and I believe I found the right thread.

I have a 22' pontoon with two 25" tubes. It's pushed around by a Mercury 115 HP 4-stroke with a 3-blade prop (Mercury Part #77340A45P15). Here's the spec sheet: http://www.southbaypontoon.com/product. ... ries=sb500

Here's my issue: At WOT (6000 RPM), I'm only able to get up to 20-22 mph (with a good tailwind). It seems that I could easily push past the 6K RPM but the throttle is as far forward as it will go and I really don't want to damage the engine.

The prop isn't labeled with a size, just the part number listed above. A google search for the full part number revealed nothing, dropping the "P15" off the end (77340A45) led me nowhere except to several eBay listings. Could the P15 be the pitch? A cross reference search on iboats.com leads me to believe this is a 14x13 prop.

Now, I didn't buy a pontoon so I could go out and race the Donzi and Fountain guys, but after all the reading I've done on this forum, I'm curious if I need to go up 2-4" in pitch. You guys with 60 and 90 horses running in the high 20's - mid 30's... Wow.

Can you guys tell me what size props you are using to achieve these speeds?

The engine has performed flawlessly.

[jmiliz]

I have a quicksilver prop with P13 at then end of the number and its a 13 pitch, however, you model number for a quicksilver(black max), 48-77340A45 shows its a 14 x 13. The 13 pitch makes more sense since you say you are at 6000rpm. You would have to go up in pitch to lower your rpm. I just broke my prop and also wondered if anyone has used the cupped ones. May prop sites recommend them for pontoons. I was also thinking of trying the Piranha prop but have read mixed reviews. Anyone else try these?