Pontoon Boat & Deck Boat Forum

I think my prop is correct.

The original prop was 13.75 x 11p. Wasnt performing great. WOT was 27 mph at 7000 rpm.
The stealership changed it to 13.75 x 15p. Now, WOT is 29.4 mph (see picture of GPS at 29.3) at 5800 rpm. Now, WOT is much more quiet, and a bit faster. This was with 2 adults, 1 child, and a slap-full tank of gas. Maybe at 1/4 tank I can hit that elusive 30 mph! Not too shabby for a two-log toon with 115 horses.

This is a 3 blade aluminum prop. Maybe more speed with stainless? Maybe more speed with 4 blade? Cost vs benefit?

I havent evaluated effects of new prop on towing a tube, yet.

In the picture, the big number is water depth. Below that is speed, and below that is water temp.

Good numbers on that rig for sure. You're right, it does seem that you are correctly propped now, for your situtation. Yo may need the lower pitch prop if you ever get another 4-6 people on board, but cross that bridge when/if you get to it.

Nice little GPS system too. Something I've considered for a while now, but can't make myself break down and buy one.

GXPWeasel wrote: Nice little GPS system too. Something I've considered for a while now, but can't make myself break down and buy one.

If I recall, the gps/sonar was pretty darn cheap, compared to color units. Well worth the
money, and well worth the time to install. I have it on my rail, without drilling. I don't want to put holes in my helm, unless I don't have a choice.

Can I get a picture of how you mounted the depth finder to the rail?

GXPWeasel wrote: Nice little GPS system too. Something I've considered for a while now, but can't make myself break down and buy one.

I just use the gps on my iPhone. The 'toon's speedo is accurate above 15, so I only need the gps for low speeds.

Red555 wrote: I just use the gps on my iPhone. The 'toon's speedo is accurate above 15, so I only need the gps for low speeds.

Well, the unit also has lake maps - without detail except shoreline, but you can save spots so you can find your way back.. It also is a sonar/depth finder.. Sees fish, gives their depth, and even can see a fishing lure.

Mounting pictures will follow.

Here's how I rigged my GPS/sonar to the railing.

You'll see I used nothing fancy for mounting it. Some flat metal from the local ACE Hardware store, predrilled mounting plate. Found in like, the same place you find hinges. The predrilled holes are the same diameter as the holes in the baseplate/mounting bracket for the unit. I can't remember if I used SS bolts/nuts/lock washers, or just standard junk.

I used a plate under the unit to give it strength when tightening the bolts. I used a plate under the rail. I guestimated the bolt length, and put it together. Look how the plates are kind of staggered, to provide as much metal under the base, then rotated position of the under rail plate to reduce injury by scraping against the metal edge. I guess I could trim off the corners, but, no need so far.

You'll notice only two of the 3 holes have bolts. No problem with vibration or movement.

It has never slipped or slid along the rail. I haven't (yet) cut myself on the metal edges.

What brand prop did they fit you with? I have the same setup with a 15 not sure diameter and have to get another. I am only running 5k at wot and engine max is 6k. I am running about 24 with two people and quarter tank. The boat has plenty power with 6 people and full tank except it sits way to low in the rear with a load. I have asked multiple setup guys and they said stainless would be throwing money away on this setup. I would think that the plain physics would help at least a minimal amount if money isn't that great a factor. I am just a little disappointed not to be running 27 or so with 22.5 feet and 115 mercury 4 stroke.

I'm not sure of brand name of prop, but I would imagine it's the cheapest one the stealership keeps in stock for their new boats.
The time I was able to record the 29 mph was with flat-as-glass water and minimal load.
On the two times I went out over the holiday weekend, the lake was very rough, and we had 6 adults and beer/food coolers, full tank of gas. The max speed, when I took time to glance, was around 24. I am able to pull two adults on tube (with same boat load) was >20 mph.

Another option for guys like us that don't want to drill holes or mount on the rail an risk it wearing a hole in your tarp. I bought an extra sst cup holder an drilled a hole in the bottom to run wires through, welded a sst plate over top mounted it this way. If u have a cup holder up top my helm has 3 cup holders, it works great takes 2 minutes to put on which I would much rather have than holes.

i use that prop too 13.75 x 15 but when i want to pull skiers and tubes i use the 14 x 14 its a stump puller and loses no rpm in tight corners pulling the tubes

Captain Jack, would it be possible to get some pics of how you have your depth finder mounted to the SS cupholder. I hate the idea of drilling holes in my console and don't want to risk tearing

the cover with a rail mounted version, although I do think it is one of the better mounting choices I have seen.

thanks........Charlie

UPDATE:

I finally broke the 30mph I've been searching for... I reached 31.1mph via gps. Not too shabby, huh? It was at night, 68 degrees, very low humidity... please pardon the picture quality, it's hard to capture an image while driving in the dark and using a camera phone with auto flash! (I didn't think to turn off the flash, duh!)

The big top number is the water depth, then speed, then water temperature...

PlaynDoc wrote:The stealership changed it to 13.75 x 15p. Now, WOT is 29.4 mph (see picture of GPS at 29.3) at 5800 rpm. Now, WOT is much more quiet, and a bit faster. This was with 2 adults, 1 child, and a slap-full tank of gas. Maybe at 1/4 tank I can hit that elusive 30 mph! Not too shabby for a two-log toon with 115 horses.

This is a 3 blade aluminum prop. Maybe more speed with stainless? Maybe more speed with 4 blade? Cost vs benefit?

The Mercury prop selector (using a generic 22-foot boat for the weight part of this) thinks you're about right where you are now.

http://www.mercurymarine.com/propellers/prop-selector/
Calculated Pitch: 14.1
Calculated Weight: 2469
Calculated Engine RPM: 6250
Calculated Boat Speed: 24.6 MPH

You might try to squeak that a little more with the 4-blade 12.8x15 but you may be at the top already. You might instead get it underskinned (maybe $350), that would give you a smoother ride but could raise the top end a little for you.

Stainless props start earning their money if you have at least 150-175 HP and running 35 or better. The faster you go and the more power you have, the greater the difference. I replaced the stainless Volvo props off my barge with aluminum props from Powertech. I went down one size (Volvo duoprops only come in sets numbered 1-8) from 4 to 3. I can hit 30 mph now, fuel milage is better and holeshot improved a lot also. I know it was the change in pitch that did it, but as far as any improvement in switching from a $500 pair of aluminum props to a $1,500 set in stainless steel, ain't worth the money.
Now if I had a newer Playcraft with a Verado 300 that cruised at 50 mph, the stainless would make a lot of difference. But not at the speeds my barge travels at!
Anyone need a slightly used set of stainless Volvo duoprops?? $500 takes them...