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Yamaha F70LA prop selection

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JimPa

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I own a 2013 Bennington 2075 GL pontoon. It has a Yamaha 70HP F70LA motor with 13.75 x 13 K aluminum prop. Full throttle I get 5700 max RPM and 18-19mph per my phone speed app. Is this normal for this size boat?
 
That's probably right in the area. How many people on board?
 
Thanks for your reply Derrick. That's with just me on board & the Bimini top down.
 
I'm pretty sure my 90hp 2009 2075 GLi had the same prop size, I think we topped out at around 23-24
 
Thanks. I guess I’m running per design then. Was hoping maybe to get a few more mph.
 
You never know, might be able to squeeze a couple more out of her. We're talking aluminum props, so not that cost prohibitive. If you have a good prop shop nearby they might let you try out a few one day. All depends how much effort you are willing to put in to get that bit extra. I would do some serious testing with your current, writing down all the stats about it (speeds at various rpms, time it takes to reach different speeds, noting cavitation in turns, 'feel' of holeshot), then compare each against those parameters. Like I said, fair amount of work, but all depends on how much boating time you are willing to devote to it vs possible gains.

For me, on my first boat, I took what the dealer put on and never thought much more about it. My next two boats I did my best research before and had them order what most were having success with and never thought much more about it. I remember a few with same setup on here got a couple mph faster, but I had such limited use of my boats that I wasn't going to worry that my 200 was doing 42-44 and someone else got 45-46. It would have meant I got to the other side of our small lake 20 seconds sooner! Haha besides, usually we were cruising at 20, or heading back to the dock at 30-35, or anchored in our usual spot.
 
My lighter 2015 model 20 SLX had the F90, and we could get a consistent 26 MPH with the wife, little dog, and me, so you are probably in the ball park with your speed and what I would think to be a heavier boat. Now, with 7 people on it one day, we were trying to outrun a storm, and I got a whopping 14-15 MPH. I had the 4 blade SS and I believe it was a 13 pitch. It had a very good hole shot, and yanked me out of the water when I skied behind it, but it was still a 90.
As Derrick stated, if you want to turn a possible couple of MPH into a hobby, then let us know how it went. Good luck.
 
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