performance problems with new rebuild

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keosports
Posts: 91
Joined: Wed Mar 13, 2013 9:46 am
Location: west palm beach

performance problems with new rebuild

#1 Post by keosports » Wed Mar 13, 2013 11:09 am

looking for advice for performance problem with my new rebuild. I rebuilt a 20' sweetwater with 22" toons, I added an engine pod transom and upgraded from a 70hp to 115hp both 20" (115 came off my 25' pontoon and went 28mph) on the new boat I am struggling to hit 25mph, it feels like something is holding me back the higher the RPMs, seems to be a lot of water shooting out the sides towards the back 5 feet of the toons. i am thinking maybe the new pod is pushing water up and over the toons, I am going to skin but would love to hear any more suggestions, I also have a spare set of 21' / 21" toons that i may modify for a 3rd toon (the new engine pod is welded on to the cross members)ImageImageImage
21' sunbird tritoon deckboat E-Tec 150
25' fiberglass deck unknown mnf. Yam 70
20' rebuilt sweetwater Johnson 115
21' monark parts boat Evinrude 60
16' tango jet boat Merc 175
12' inflatable catamaran Yam 9.9
10' hobie sport mirage 1 Me-power

Bamaman
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Location: NW Alabama--Tennessee River

Re: performance problems with new rebuild

#2 Post by Bamaman » Wed Mar 13, 2013 12:56 pm

Are you able to redline the newly installed engine? Is it propped right?

Your problem may be the shape of the new engine pod dragging thru the water--shaped like the front of a toon. The design from the pods on my two boats seem to be much less substantial and more aquadynamic (if that's a word). The motor might also be running too deep in the water.

The best way to get more performance out of any pontoon boat is to get the nosecone out of the water. That means putting your engineering resources into lifting strakes.
'12 Bennington 24' SSLX Yamaha 150

margaritaman
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Location: Florida

Re: performance problems with new rebuild

#3 Post by margaritaman » Wed Mar 13, 2013 7:55 pm

How is your RPM?
Cruising the salt waters of East Florida.

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keosports
Posts: 91
Joined: Wed Mar 13, 2013 9:46 am
Location: west palm beach

Re: performance problems with new rebuild

#4 Post by keosports » Thu Mar 14, 2013 4:58 am

25mph @ 5500
21' sunbird tritoon deckboat E-Tec 150
25' fiberglass deck unknown mnf. Yam 70
20' rebuilt sweetwater Johnson 115
21' monark parts boat Evinrude 60
16' tango jet boat Merc 175
12' inflatable catamaran Yam 9.9
10' hobie sport mirage 1 Me-power

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Bamby
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Joined: Mon Nov 03, 2008 7:30 am
Location: Near Wheeling W.V.

Re: performance problems with new rebuild

#5 Post by Bamby » Thu Mar 14, 2013 6:29 am

underside pontoon boat.jpg
underside pontoon boat.jpg (193.11 KiB) Viewed 5025 times
I've got a similar situation as yours under my boat but fortunately mine is much smoother. The third pontoon being deep in the water will split or turn a huge about of water to the sides and the underside of the deck. In your case you've got some pretty extensive resistance impeding the forward movement or momentum of your boat. IMO under-skinning could and would improve you situation but how much you'd speed actually gain is above my pay-grade. But you should see better boat performance, smoother quieter ride, and improved fuel economy for you efforts which are all wins at the stage of the game you're at.
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Boating the Muskingum River
1972 35' Crest Pontoon Houseboat
2007 90 hp. Yamaha

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curtiscapk
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Location: OP KS\Hillsdale Lake

Re: performance problems with new rebuild

#6 Post by curtiscapk » Thu Mar 14, 2013 7:06 am

Nice work Bamby!!

and if you look at his lower unit the prop isn't much lower than the pod... :smoke
Craig and Paula
"THE FLOATER" rebuild Spring 2013
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94 Party Barge 24' 115 merc
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keosports
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Joined: Wed Mar 13, 2013 9:46 am
Location: west palm beach

Re: performance problems with new rebuild

#7 Post by keosports » Thu Mar 14, 2013 9:37 am

thanks Bammy, the unknown stuff on the side was what was left over from my pvc sheet underskinning that did not work out well, it was free so i tried it out, I have a much more rigid/ stronger material I am going to try next. I just hope that is the most of my problems. if all goes well me next move i am thinking is to cut down and put strakes on one of my spare 21' logs to 12' to bolt up in front of the pod, does this sound like the right thing to do? I looked into a water glide but was told it would lift the boat 5" out of the water and was worried my 20" would not be in the water enough.
21' sunbird tritoon deckboat E-Tec 150
25' fiberglass deck unknown mnf. Yam 70
20' rebuilt sweetwater Johnson 115
21' monark parts boat Evinrude 60
16' tango jet boat Merc 175
12' inflatable catamaran Yam 9.9
10' hobie sport mirage 1 Me-power

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keosports
Posts: 91
Joined: Wed Mar 13, 2013 9:46 am
Location: west palm beach

Re: performance problems with new rebuild

#8 Post by keosports » Thu Mar 14, 2013 9:39 am

curtiscapk, i got 2 bolt hole notches i can lower the motor so i will try lowering that also (prob drop it about 2")
21' sunbird tritoon deckboat E-Tec 150
25' fiberglass deck unknown mnf. Yam 70
20' rebuilt sweetwater Johnson 115
21' monark parts boat Evinrude 60
16' tango jet boat Merc 175
12' inflatable catamaran Yam 9.9
10' hobie sport mirage 1 Me-power

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keosports
Posts: 91
Joined: Wed Mar 13, 2013 9:46 am
Location: west palm beach

Re: performance problems with new rebuild

#9 Post by keosports » Sun Mar 17, 2013 10:47 am

got the boat all underskinned , lowered the motor and took it out, got up to 28mph @ 5000 with no water turbulence,next move is to modify and bolt on my extra pontoon, going to cut it down to 12' to fit in front of the engine pod. I am not sure how much performance the 3rd log is going to help but if it adds considerable buoyancy I will be shopping around for a 200hp.
21' sunbird tritoon deckboat E-Tec 150
25' fiberglass deck unknown mnf. Yam 70
20' rebuilt sweetwater Johnson 115
21' monark parts boat Evinrude 60
16' tango jet boat Merc 175
12' inflatable catamaran Yam 9.9
10' hobie sport mirage 1 Me-power

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