Welcome Guest - Sign Up today
Welcome Guest - Sign Up today
Store Links Mobile - Shop Now


No announcement yet.

Pontoon Conversion to an Inboard/Outboard

This topic is closed.
  • Filter
  • Time
  • Show
Clear All
new posts

  • Pontoon Conversion to an Inboard/Outboard

    I have had a few people ask me to do a build thread on my I/O pontoon that I built so here it is. (first off I know my spelling and grammar sucks so just look that the pictures if you’re a grammar nazi)

    First off lets start with the back ground story. When I got married I acquired the pontoon boat very similar to this one but only 16 feet that was complete rotten out and needing everything from the floor up. Took me 2 summers of getting things the way I wanted and realizing how much I like having a pontoon of my own. Well fast forward to last summer and one of my father in-laws brothers decide that he wanted the pontoon left at the cabin for his drunk ***** to use. I end up getting paid for the money I spent on the boat but never the amount of time I put in to it.

    I had to “give” the other boat back last August, so I have been searching CL and other spots since then. I found this boat in SE Iowa February 26th and drove down and got it March 1st , left the Minneapolis Mn at 4 A.M to try and make it back before dark. When I was talking to the guy on the phone I asked him what condition the tires and lights are in since I have a 600 mile drive back to Minnesota with it. I got the typical response everything works great. I get down there both tires are flat and dry rotted and the lights don’t work. Got the tires aired up shoveled 4” of leaves off the pontoon and head home doing 65mph so I wouldn’t blow the tires up.
    I introduce you to a 1989 24” Bass Buggy with a 40hp Evinrude.

    Made it home just before dark.

    At this point I had a lot of “good” ideas running thru my head. I wanted a big boat that would go fast(30mph) and be quiet when it idles down. All on a budget. (didn’t have 10k to spend on a 150hp 4-stroke outboard)
    Again CL came into play and search for the next month for an old boat that had the famous GM 4cyl in it. I found this one 2hr away, gave the guy $500 for it.

    1972 “something” with a Mercruiser outdrive and GM 140hp 3.0l

    Boat ran really well for being so old

    Removing motor from boat the “easy” way

    Getting rid of boat that no longer floats
    Last edited by Bob_VT; August 14th, 2012, 03:03 PM.

  • #2
    Re: Building of an I/O pontoon (lots of pics)

    Next was the start of a love hate relationship with my TIG welder. Need to build a 3rd like pontoon that would hold the motor and keep it water tight along with the outdrive. Two 4x8 sheets of .125 5052 alum and stop time in Soildworks laying it and we have something that will work

    The part the motor and out drive need to be 2” thick to support and give the right distance from motor to outdrive. Also need to be tipped back 10’15 degrees to give proper trim angles.
    Building the stern for the 3rd pontoon and test fitting the outdrive.

    Over 60ft of TIG welding 2 tanks of Argon and 10 pounds of .125 filler rod shes mostly done. Motor set in place.

    Meanwhile while taking breaks from welding I stripped the pontoon down to its frame and test fitted the new 3rd pontoon.


    • #3
      Re: Building of an I/O pontoon (lots of pics)

      Next was getting the motor in 3rd pontoon and getting the frame welded to the old pontoon. Added a few pics so you can get an idea how this was done.

      Woke up from a dream at 1am of having this boat all done and backing it into the water and it just kept sinking. That follow night I went to the lake a floated it for the 1st time. Sits perfectly level and very stable in the back. Even with an 800 pound motor and two guys on the back. (got a lot of looks from people when I was doing this.

      Next was getting the floor and carpet on. You can also see that I add an infloor gas tank that holds 32 gallons.


      • #4
        Re: Building of an I/O pontoon (lots of pics)

        At this point I also need to start the body work on the railing as I wanted these to be High Gloss Black. This is where things started to get out of control. Having a neighbor who does auto body work is not always a good thing. One night of talking to him telling me over and over “your building a hotrod pontoon you have to paint it hot rod colors” I gave in to is suggestions an we came up with black railings with a 2012 BWM orange for the center counsel and the sides.
        Painting of the center counsel

        Between stripping and sanding the railings down for paint (well over 80hrs) I finished the center counsel and got the pieces of alum for the gauges done and anodize. Really like how these turned out.

        After getting the center counsel back from paint I came the conclusion that this pontoon is turn out way to nice to sit outside while I’m building it. So off the trailer it came and into my 18x32 garage. Still had just enough room to fit the wifes car in every night.

        Over the next weekend I got it all wired up and throttle and steering hooked up. First start up video (she runs).


        • #5
          Re: Building of an I/O pontoon (lots of pics)

          We painted the railings in 4 sections each sections took 2 nights to do the primary then the paint.

          Railings and orange sides on the boat. At this point I just cant wait to get it on the water.

          Before I could put it back on the trailer I need to paint and replace the bunks on the trailer. Since my truck was stuck in the back yard and I need 4 18’ boards brought home a TDI VW Golf should work right? (for all the people saying this is not safe I live less than a mile from Menards so go pound sand)

          Next was getting it slide back onto the trailer and out of the garage. As you can see I didn’t have a lot of room and this was rolling it out on the trailer hubs.

          On the trailer with the sides on.


          • #6
            Re: Building of an I/O pontoon (lots of pics)

            My goal during this entire build was to have it on the water by June 1st. Surprisingly I was a week ahead of schedule. Memorial weekend was her main outing and she did great. Had one small issue, when you get moving above 25mph it would push water thru the gas tank vent and into the tank. That was easily fixed.

            As I said earlier on of my goals was need to be quiet when idling and be able to go fast when I wanted to. Well with just me in it with a bent up prop with the wrong pitch it did 27mph. Once the bottom skinned ,lifting stakes on and the correct prop I should be good for atleast 35mph.
            Here is a few videos of memorial weekend.


            • #7
              Re: Building of an I/O pontoon (lots of pics)

              During this whole build I was struggling on what I wanted to do with seats and as the pontoon transformed to what it is today. I knew I could not just throw off the shelf seats on this boat. Thru a lot of research I found the company that builds most of the seats for pontoon boats. I order up the seats and was told I would have them in 3-4 weeks. 2 weeks go by and they call me up saying there done.
              Had them shipped to work and man I was like a kid in a candy store on boxing them.

              Nice plush captains chair.

              Installed on the boat .

              This brings it to where it sits today.
              I have some small task that need to be completed as I have time. Some of the bigs ones are a travel cover is getting made to keep the interior nice.

              A bimi(sp) top is getting built or bought. Thanks to Unbroken’s FB page the other day I want to build something like this.

              But it will more then likely end up like this(stole the one off my old boat)

              Another axle on the trailer as this one right now hates life.
              Dogs house over the motor
              Swim platform off the back.

              I must say building this boat almost caused me a divorce with my wife since I was always out working on it. But the first time out she figured out there is a method to my madness. She was/still is a little pissed that I went over the 6k budget that SHE set and that the seats in the pontoon are nicer then the ones in our house.

              Now that you all have read this I’m looking for name ideas.
              Last edited by Bob_VT; August 14th, 2012, 01:59 PM.


              • #8
                Re: Building of an I/O pontoon (lots of pics)

                Thanks it has been truly a labor of love. Between burning my hands TIG welding to my hands going numb from sanding the railings its nice to go back and look and see how far its come.

                As for an understanding wife she was anything but helpfully. There was alot of fights and arguments but at the end of it all she really likes it now. Maybe someday she will realize that not all my ideas are stuipd. Maybe

                I currently dont have a "dog house" over the motor. I'm currently working on the dog house and it will have the blower built into it. I have the old one off the boat that seems to work good.
                Last edited by Bob_VT; August 14th, 2012, 02:06 PM.


                • #9
                  Sign up today
                  Re: Building of an I/O pontoon (lots of pics)

                  Undate just got back from a two week vacation with her ad no issues and burned about 60 gallons of fuel thru here. I have been out on the water every weekend since the memorial weekend and have burned well over 120 gallons thru her. She's working great.
                  Have done a few things along the way and still have a few more to do.
                  Had a custom cover made to protect the seats.

                  Made a custom made trailer to haul this big pig around.

                  Added a swim platfourm off the back along with a ladder. All the aluminum is out to get black anodize right now so I dont have any current pics.

                  You can also see in the middle of the swim platfourm a made a thread bose to screw in a ski pole. While on vacation I went skiing behind the pontoon.
                  Last vacation had to take the camper with us since we where camping for 2 weeks and had the dogs with us. 68.5 feet of fun. Truck pulled it really well set the cruise at 65mph and let the diesel work. Got about 12.5mpg pulling.

                  I also added lifting strakes but I didnt take to many pics of installing them. All I can say is it was not fun but it added 5mph to my top speed.

                  I'm mostly done working on her for the yr. Next yr will be a new hyrdauilc Bimini top and a water cannon