Moving Engine Mount Aft

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PenBayCruiser
Posts: 3
Joined: Thu Jul 12, 2018 6:47 am
Location: Maine

Moving Engine Mount Aft

#1 Post by PenBayCruiser » Thu Jul 12, 2018 2:23 pm

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[img]I have a 1998 Aqua Patio 24' boat. The boat is stripped to the deck and am replacing the carpet with vinyl. The engine mount currently is about flush with rear of the pontoons and the deck has a large cut for the outboard to tilt into. I'd like to move the engine mount rearward to eliminate the cut out. Then the space will be used as a small deck. The outboard is a 2003 Mercury 40hp 2 stroke (about 170 lbs). Aside from replacing the interrupted aft cross member with a continuous member and longer steering/shift/throttle does any see potential problems? The fence on the starboard side will be modified and sun deck eliminated. Port side fence encloses the fuel tank so that will be retain and the cushion on top removed then covered with vinyl. Any input would be appreciated!

Bamaman
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Joined: Fri May 06, 2011 1:44 pm
Location: NW Alabama--Tennessee River

Re: Moving Engine Mount Aft

#2 Post by Bamaman » Thu Jul 12, 2018 3:28 pm

Leave it like it is. The cutout muffles the.sound.of the motor. I have a Starcraft styled like it, and my Yamaha 115 horsepower two stroke planes at 2800 rpm's and is very, very quiet.
One problem with small motors is that they are relatively loud because they have to be run so hard.
'12 Bennington 24' SSLX Yamaha 150

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Marc K
Posts: 74
Joined: Fri Jun 01, 2018 4:35 am
Location: Cedar Creek Lake, TX

Re: Moving Engine Mount Aft

#3 Post by Marc K » Thu Jul 12, 2018 4:20 pm

I have to agree with Bamaman!

The stern of my pontoon is setup like your picture except that the sun deck above is hinged as one piece. Sound level difference is dramatic with the lid up/down. It really is a huge difference in motor and water noise on my boat.

Plus, I use the "shelf" above the transom for some more battery power in a great center line location to counterbalance a crowd up front!

Marc
25' Crest II DL
Yamaha F115 4 Stroke

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bansil
Posts: 339
Joined: Tue Nov 01, 2016 4:10 pm
Location: Watâ'gi lake...Beautiful Waters

Re: Moving Engine Mount Aft

#4 Post by bansil » Thu Jul 12, 2018 4:56 pm

My input is this:

Notice you sit at 1/2 pontoon now? You move that engine back and DO NOT add a 3rd pontoon OR engine pod (extra drag in this case) you will be so nose light it wouldn't be funny, the rear will slap and crossmembers will drag water and .....make it a slow beating on your soul.... :mrgreen:

But

I could be wrong...just look at wt and fulcrum points

PenBayCruiser
Posts: 3
Joined: Thu Jul 12, 2018 6:47 am
Location: Maine

Re: Moving Engine Mount Aft

#5 Post by PenBayCruiser » Thu Jul 12, 2018 5:39 pm

Good point Bansil. The cantilever effect is a consideration. And if the Yamaha 115 V4 (330 lbs) were going back on then a big consideration. Fortunately the 03 Mercury 40 hp weighs around 170 lb which should help that situation considerably. Losing 2/3 of the sun deck (starboard side is currently a tilt up privacy room and weighs 50-60 lbs) will also remove nearly 80-100 lbs. The aft sheet of decking may be replaced with a sheet of Coosa board 26 that I had for another project for more weight savings. Lots to consider.

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bansil
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Location: Watâ'gi lake...Beautiful Waters

Re: Moving Engine Mount Aft

#6 Post by bansil » Fri Jul 13, 2018 3:56 am

That is a lot of wt savings!

gerard143
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Joined: Thu Jul 20, 2017 7:03 am

Re: Moving Engine Mount Aft

#7 Post by gerard143 » Sun Jul 15, 2018 8:40 am

I moved my transom back on my restore and eliminated the cutout. Replaced the cutout crossmember with a full. I also went 25 horse larger (115 horse) and added about 100 lbs in motor weight. In about 3 weeks i'll be on the water and i'll let ya know how she does!

Also keep something in mind, all the newer motors are taller from the mounting bracket upward. This means when you trim up you have issues hitting the cutout and the sundeck. The new evinrudes can trim up 80+ degrees which makes the issue even worse. IMHO removing the cutout is a good way to future proof your remodel and also gain some serious storage room. I'm glad i did it. With a motor your size and the weight savings you mention i'd have zero qualms moving that transom back.

You can see my full rebuild so far here: http://www.pontoonboatforum.com/1987-ha ... c8799.html

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