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Old 07-05-2015, 07:17 AM   #1
thinkxingu
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Default Props and Inflators

Hi!
As the title suggests, I have a question on props and Inflators.

Props: we've got a 22' pontoon with 70 hp Suzuki and are wondering if different prop would make a noticeable difference in performance. Current one has one sight ding but otherwise perfect.

Inflators: bought a Big Mable towable and it's, well, big! Wondering if it makes sense to store it in the changing area and blow up when needed, but the inflator I have is 120v and we don't have a 12v outlet (at least not at the control center or that I know of). Suggestions?

Thanks!

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Old 07-05-2015, 07:36 AM   #2
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Props can make minor differences. You're essentially trading low-end torque and take-off speed/power for top-speed/cruising speed.

If your goal is to have more speed/power in the range where you are towing people on the tube, then you can switch props for better low-end torque, but you're going to lose top-speed.

If your goal is a faster cruising speed you are going to sacrifice power in the "hole shot".

And of course this is all limited to within reason. Your 70HP motor is probably a little anemic for that boat and is going to be best for casual cruising more than anything.
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Old 07-05-2015, 07:57 AM   #3
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How much does material matter? Specifically, I have seen mention of stainless props, etc. With my wife, father, and two chillens, we cruise about 21 mph at 5k RPM.

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Old 07-05-2015, 08:21 AM   #4
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Stick with aluminum. Stainless steel props are better for higher hp boats as the theory is aluminum will deflect under a load.

On winni the other good thing about aluminum is that the prop will give if you hit a rock as opposed to your gears taking the brunt of the hit.
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Old 07-05-2015, 08:34 AM   #5
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Default Props

This subject is a discussion and a half! I would suggest you visit the Mercury prop website. Very informative and if you don't pay attention confusing.

If the current prop gives you maximum rpm at WOT (wide open throttle), then the pitch is right. Marinas do a pretty good job at pairing props with the boat and motor combination, but there are times you may want to check.

Normally the standard prop is designed to give good cruising and GPH(gallons per hour). A stainless steel prop will not flex like a composite or aluminum. The flex will allow 'more torque' out of a hole. A stainless steel being rigid will give you more top end and depending on the make and model more torque.

Increasing the pitch by 1" normally add 200 rpm, likewise decreasing the pitch 1" results in 200 rpm drop.

3 blades are great for normal use. 4 blades and more adds more torque and great for water sports. You will lose top end but not much. Ever see a bass boat literally jump out of a hole and hit plane in seconds? Chances are he has a 5 blade prop.

Going to a stainless prop will cost you about $600. I keep my standard aluminum as a spare. Different makes and or models will vary in price and adding a blade will up the ante.

In a nutshell ask your marina what will be a good prop for pulling water toys and go from there.
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Old 07-05-2015, 08:55 AM   #6
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Can't help much with the prop, and my "Inflator" suggestion will not work out on the water. ( maybe I should just go back to reading post )

For inflating stuff it's hard to beat an old Electrolux canister vacuum. Switch the hose to the "blow" end and you will be up and floating in no time. And it doesn't matter that the beater-brush is worn out
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Old 07-05-2015, 09:06 AM   #7
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"Increasing the pitch by 1" normally add 200 rpm, likewise decreasing the pitch 1" results in 200 rpm drop."

I believe it's the other way around.
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Old 07-05-2015, 09:32 AM   #8
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Can't get much more out of that 70HP no matter what kind of a prop you use.....might as well trade for a nice 150.
Inflating towables with a 12v takers forever,I'd just tow it behind the boat or strap it onto the bow.
All that aside,it's just fun to be out there.
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Old 07-05-2015, 10:03 AM   #9
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Get yourself an Intex Double Quick pump for the tube, they require no power and fill tubes really quickly. I got mine at Parafunalia years ago and it has held up really well. I would not bother with a new prop unless yours is badly damaged.
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Old 07-05-2015, 11:14 AM   #10
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I know the engine is a limitation, but it's our first boat so we went a little conservative (on power AND price). Just didn't know if I was missing an opportunity.

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Old 07-05-2015, 12:03 PM   #11
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Assuming you meant 12v volt inflator, you can get power ports with alligator clips to go directly to a battery. Easily converted to a permanent mount but I'd advise adding a fuse if you do that.

Good luck!
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Old 07-05-2015, 04:23 PM   #12
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OK, so 12v Inflators aren't worth the money and the prop won't make much of a difference. Check!

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Old 07-05-2015, 05:43 PM   #13
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Quote:
Originally Posted by thinkxingu View Post
OK, so 12v Inflators aren't worth the money and the prop won't make much of a difference. Check!

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I have a Coleman 12 volt rechargeable inflator that I have had for 5 years now and it works great. Fills up 3 person tubes to full capacity in no time! When I first bought it I never expected it to last more than a season as it was very cheap but here we are 5 years later and that thing still works great!

Dan
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Old 07-05-2015, 07:03 PM   #14
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^ I've read that the rechargeables aren't great because they only plug in to charge, not to use.

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Old 07-05-2015, 08:42 PM   #15
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Quote:
Originally Posted by thinkxingu View Post
^ I've read that the rechargeables aren't great because they only plug in to charge, not to use.

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The one I have can only be used when not plugged in charging and only when running off the battery. Like I said above. It was very inexpensive and has worked great going on 5 years now.

A small correction, it's not 12 volt but recharges off a standard 120V household plug.

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Old 07-07-2015, 03:10 PM   #16
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The problem is you are using performance and pontoon in the same sentence. Only until recently like in the past 5 years have they started to make pontoons that can really get up and go especially with the tri toons, but the original pontoons are motorized swim rafts and simply are not a great platform for playing around with pulling anything. You can but...

That said the pitch of a prop can indeed make a difference. Like anything there is a give and take with the pitch, although there may be a prop that is best optimized for the motor, that may not take into account what the motor is attached to. Take your 70 HP outboard, there is a big difference with that being on a toon versus say a 17' aluminum dual console fishing boat (for example). Usually if you are interested in another pitch some marinas will let you try them out of course if you smash it you own it. I wouldn't waste any money on a stainless prop those are primarily for high performance applications. I put one on my 4.3L stern drive and it made 0 difference other than it looks cool!
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Old 07-08-2015, 06:54 AM   #17
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Your motor has a factory rating for top r.p.m. (revolutions per minute) at w.o.t. (wide open throttle). Check with the manufacturer to see what this number is. Then, run the boat and see if you hit max rpm. If you do, then you have the right prop.
A 70hp on a 22ft boat sounds a little underpowered for what your trying to do. I think your going to find that your need would be better met by going with a larger motor on you boat, a 90hp or 125hp, if allowable per manufacturers specs, will make a bigger difference.
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