pontoon with 70 hp johnson
Moderators: Redneck_Randy, badmoonrising, lakerunner
pontoon with 70 hp johnson
hi, I recently bought a 1993 sweetwater 24 ft pontoon without an engine on it. I also recently bought a 2000 Johnson 70 hp and put on it. everything seemed fine with just me and my wife on it but when more people and more weight it really struggles and uses a lot of fuel. I did some research and found that the motor is supposed to be installed with the cavitation plate even with the boats transom. I didn't know this when installing the motor and put it down as far as it would go which is about 6 inches below the transom as the motor is a long shaft. what negative effects will there be having the motor this low? I plan on raising it up soon but just wanted to know what problems it would cause? thx, chris
1993 24' SWEETWATER
Suzuki 150 HP
Suzuki 150 HP
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- Posts: 241
- Joined: Wed May 10, 2017 10:23 am
- Location: Cincinnati Ohio
Re: pontoon with 70 hp johnson
I'm sure someone with more knowlege than me will come one soon. However, I have a 1988 Harris with a 1997 Force 75
I'll have to look at my picture (unfortunatly my boat isn't close.) to see where the cav plate sits. Mine will do 18-19 mph (GPS) with 7-8 people on-board.
So I think your on to something bringing it back up. Mine has some space to go lower so I know it is up high compared to yours
best pic I have on this machine
I'll have to look at my picture (unfortunatly my boat isn't close.) to see where the cav plate sits. Mine will do 18-19 mph (GPS) with 7-8 people on-board.
So I think your on to something bringing it back up. Mine has some space to go lower so I know it is up high compared to yours
best pic I have on this machine
My rebuild thread.
http://www.pontoonforums.com/viewtopic.php?f=16&t=24807
http://www.pontoonforums.com/viewtopic.php?f=16&t=24807
Re: pontoon with 70 hp johnson
it should be just under water when your running, lower may add drag and slow you down a bit
If it aint broke your not having enough fun
James & Deb
1988 Riviera Cruiser 15 HP Mariner
05 Silverado Z 71 V8 5.3
James & Deb
1988 Riviera Cruiser 15 HP Mariner
05 Silverado Z 71 V8 5.3
Re: pontoon with 70 hp johnson
Does your boat have a tech? If so what are the numbers? Most of the issues you are describing also can reflect back to your prop. If you're attempting to run too tall of a prop performance may be marginal but acceptable under a light load and get progressively worse when loaded just as you're describing. If it's bad enough you might even get a whiff of raw gas exiting the engines exhaust because the so loaded up and lugging that it simply can't burn it all cleanly. If this should be the case you really need to get it cleared up before serious harm comes of your motor.
Respect Our Recreational Resources
Leaving Only "The Footprints of Your Passing"
Boating the Muskingum River
1972 35' Crest Pontoon Houseboat
2007 90 hp. Yamaha
Leaving Only "The Footprints of Your Passing"
Boating the Muskingum River
1972 35' Crest Pontoon Houseboat
2007 90 hp. Yamaha
- curtiscapk
- Posts: 5401
- Joined: Mon Nov 10, 2008 8:31 am
- Location: OP KS\Hillsdale Lake
Re: pontoon with 70 hp johnson
Yes you need a TACH so we now your RPM's.....
Craig and Paula
"THE FLOATER" rebuild Spring 2013
viewtopic.php?f=2&t=15328
94 Party Barge 24' 115 merc
Turning Point hustler 14 x 13 prop
22mph gps 3 people
12 F150
Overland Park Ks
Hillsdale Lake, KS
"THE FLOATER" rebuild Spring 2013
viewtopic.php?f=2&t=15328
94 Party Barge 24' 115 merc
Turning Point hustler 14 x 13 prop
22mph gps 3 people
12 F150
Overland Park Ks
Hillsdale Lake, KS
Re: pontoon with 70 hp johnson
thanks for all the replies everyone. I tried moving the engine up but it didn't help. I also tried going from a 14x11 prop to a 14x9 and it didn't help either so I sold the motor and I'm going to put a 115 hp on it as 115 is max rating for my toon. thx again, chris
1993 24' SWEETWATER
Suzuki 150 HP
Suzuki 150 HP