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  • Pontoon Project - Questions

    Hello all,
    Completed my 20' Rivera Cruisers Pontoon project, turned out amazing. I'll send pics when I can, until then I have a few questions if I may..
    Firstly, I removed the front wrap around seats and replaced them with bucket seating (shed some weight up front). I installed a slim hydraulic power lift which gives me about a 4" setback. I upgraded form a 50HP Johnson to a 90HP 2-Stroke Merc (about 100LBS heavier). I installed full seating at the stern. From the factory, the fencing ends all the way back to the stern and I have about four feet of playpen (bow). My question: The pontoon seems stern heavy, that is when I'm underway the stern "drags" and there's much "spray" port and STRBD. I have room to move the engine 6" forward to offset weight, or I could move the fencing and all seats forward so there is 2' of playpen. What do you all think? Does anyone have some specs on this as far as optimal balance points? I would like to get that stern up about 3" but not too much bow drop. Thanks!

  • #2
    I just did a Johnson 50 to Honda 90 upgrade as part of my recent major refurb on our boat (deck/carpet/console/furniture). I also moved the fence forward 39" because I wanted extra room in the back to access the new swim ladder installed on the RR corner, as well as easy access to ski ropes etc. Considered the deck forward of the fence a waste of space, so I left just enough to walk, about 10" or so. I did not move the helm. LOVE that move - until somebody really big (300lb+) wants to ride up front. The 24" tubes start running kinda low at that point. Nothing dramatic, just noticeably lower than normal. We now need to pay attention to how the boat is loaded in some conditions, which is really not that big a deal. We have an L shape seating arrangement mid ship and our larger passengers need to use that. Other than that, the move worked out beautifully. LOVE the new ladder and easy access to the engine area. If I had a chance to do it again after using the boat for a while, I likely would not have moved the fence quite as far, maybe leave something like 18" in front of it.

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    • #3
      Thanks much for your reply.. Useful info for the next project this winter.. May I ask your current MPH with the 90HP? I have a 13 1/4 x 15 and run right around 28MPH on GPS with a 13 1/2 x 17 about the same maybe 29MPH with the wind. I think I can dramatically increase MPH by some stern lift. I'm thinking: Sealing the POD with an access cover on the top to reach motor bolts if necessary. I think this may provide some additional buoyancy such as 1/4 of a third pontoon. I will definitively follow you advice on moving the fence forward, I ws actually thinking moving it about 12" forward, but moving the POD and motor 7" forward as well. Your thoughts?

      Thanks..

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      • #4
        Lightly loaded (just me, the battery, 6 gallons of gas, and the life jackets) I'm turning 100rpm over the max rated rpm for the engine at 6100, running 24-25mph on the GPS with a 13 3/4x13 OEM Honda prop. So it's a pretty peppy rig for what it is. It's at 20mph before you know it! Next prop we'll go with a 15" pitch probably.

        I was considering moving my pod back a little, but was shy of what that might due to the weight distribution and couldn't envision what advantage that move might provide. Would be different if I had bigger tubes like the newer boats. I should mention that I found the rear most cross member sagging - even though it had never had anything but the 50hp on it. So I turned it upside down and reinstalled it, while adding an extra cross member of about the same size about 12" in back of that one - out of concern for the extra power and weight I was bolting on the back.

        You're considering the move forward to raise the tubes up in the water a little? Other than that, not sure why you would do that/what advantage that may provide.

        Thinking sealing the pod is looking for a potential headache down the road (potential for leaks, and ability to detect them). Not sure about yours, but mine doesn't ride deep enough in the water to provide much in the way of extra flotation. -Al

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        • #5
          Interesting..
          15"P should work very well for you, dropping your RPM's about 200, you should pickup a desirable amount of MPH. I would look for the largest diameter 15"P you could find. I found that the Solas props give you very good performance for the price. I also run a Merc Vengence 13 1/5 x 16 SS that runs out nice and I notice an increase in MPG.
          So to the point of sealing the POD.. I noticed the new Pontoon manufacturers are sealing PODS to create more stern lift while underway. I'm going to try that in addition to moving the motor forward. I now a good welder and we will test the seal with 20LBS air overnight. The reason of moving the motor forward, I mentioned I have a hydraulic lift which sets the motor back 4 inches and also added weight to the stern. My plan is to move the motor forward to the location to the original transom position, which would be about 4" to 5" .. I'm hoping this and moving the fencing forward will move enough weight forward so the stern of the Pontoon is not touch the surface of the water while underway. It appears that the upper most POD supports are riding on the surface causing the overspray from side to side.

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          • #6
            Oh yah, you're back end running quite a bit deeper than ours. At rest, empty, water line is close to half way up on toons here. Maybe not quite. Bottom of pod maybe 2" deep.

            If you're running that deep, I think you have a good plan. I might be tempted to move it even further forward, maybe 12".

            At speed, there are some spray deflectors about half way up on each side of the pod on ours. They do a nice job with the spray, and maybe even provide a little lift. Maybe not a bad plan to add them to yours if you don't already have them.

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            • #7
              Gotcha.. 12" might be about right.. My toons are a bit passed halfway and the POD is a good 3 to 4" into the water. Unfortunately, my toon came with no spray deflector(s), but planning to add them this winter. Could I ask how far down your deflectors are from the top of the POD and how wide, I read yours is about halfway up, but you could have a different POD than I? Your right, should add some lift there too. Have you looked at underskinning? That seems to be quite a project. What did you use for flooring? I used the Sherwood XL, came close to installing COOSA composite but seemed rather costly. Looking forward to winter project once again. I USED to be a Mercury factory mechanic in my youth, so another project this winter is going through the motor and freshen it up.

              Comment


              • #8
                Spray fins are maybe 6" wide and 24-30" long. They are mounted at a 90 degree angle to the pod (reinforced with 2"x1/4" angle alum. because the trailer keeps tearing them up), which leaves it at about the right angle to control the water nicely. Thinking the trailing edge might be about an inch lower than the front, but let me get back with you on that and the mounting height (too dark to see at the moment).

                I bit the bullet and went with the best ply and flooring I could find. Really like this boat, and getting old enough where doing all that's involved again is not real high on my list.

                Not really much interest in under skinning. I need to go fast enough to throw the kids off the tube on occasion (after lulling/boring them for a while, LOVE to catch them by surprise!), and we're there now as long as we don't try to take a crowd of "heavies" with us. We live on a lake, so I try to keep the number of people on board to just 3 when tubing, including myself. They can take turns, or just watch from shore.

                Do all my own engine work as well. Got a great deal on this Honda 90 as it had been sitting for quite a while, and thus in need of a complete major "re-service". Took me 3 tries to find all the crud in the 4 carbs (Honda Idle jets are incredibly small). New pump, resealed the lower unit, t-stat, new fuel lines, control cables, etc. If you've spent some time playing with these, you know the drill. Results well worth it, and I still have less than 2K into it.... The sale of my old 50 nearly paid for it! -Al

                Comment


                • #9
                  Al,
                  Thanks for the Fin info.. I'll lay this out on paper, I'm a linear thinker and kinesthetic, so pics are my thing.. I've been taking many pics of Caribou Pontoons underside and dimensions to try to work all the geometry through for this winter. The Caribou Pontoon hauls the mail, so I'm trying to find what separates' them from, say, the Benningtons, I think based on what you've described your up there with the Caribou. I too LOVE my Toon, its a dated Rivera Cruiser, which at their time (still are) great riding and performing Pontoons . I smiled when you said getting old enough.. I'm in my 60's, great shape, but the projects ahead seem a bit more monumental than two years ago. I'll work through this as perfection this winter and hopefully this will be the last year of semi major re-construction, still excited for the winter nonetheless. I do have four sons in their 20's and 30's that will be getting texts on this soon. Where did you end up buying your seating? I went through PontoonStuff (Premier) and LOVE the quality.

                  Comment


                  • #10
                    Originally posted by pbxcomm View Post
                    Interesting..
                    15"P should work very well for you, dropping your RPM's about 200, you should pickup a desirable amount of MPH. I would look for the largest diameter 15"P you could find. I found that the Solas props give you very good performance for the price. I also run a Merc Vengence 13 1/5 x 16 SS that runs out nice and I notice an increase in MPG.
                    So to the point of sealing the POD.. I noticed the new Pontoon manufacturers are sealing PODS to create more stern lift while underway. I'm going to try that in addition to moving the motor forward. I now a good welder and we will test the seal with 20LBS air overnight. The reason of moving the motor forward, I mentioned I have a hydraulic lift which sets the motor back 4 inches and also added weight to the stern. My plan is to move the motor forward to the location to the original transom position, which would be about 4" to 5" .. I'm hoping this and moving the fencing forward will move enough weight forward so the stern of the Pontoon is not touch the surface of the water while underway. It appears that the upper most POD supports are riding on the surface causing the overspray from side to side.
                    While underway my Pod does not have water in it anyway I don't think?

                    Comment


                    • #11
                      I checked mine while my son drove and same, no water, except when stopped then it fills to the water line and has to drain at takeoff.. Always wondered the logic behind allowing the POD to fill. I think I read on this forum that a member calculated the difference between an average size POD sealed/unsealed. If I recall, sealed yield to 100LBS of lift from the sealed POD, about the difference between our 50HP and a 90.. Although I think the difference between my Johnson 50 and the Merc 90 was around 115LBS. Anyway, this is what prompted me with the idea of sealing the POD. Seems like a win/win more buoyancy with no water to discharge during takeoff quicker plane (in theory. Oh, my hydraulic lift added another 25LBS, but I love it very useful with multiple people on board.. Good choice on the Honda BTW..

                      - Marc

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                      • #12
                        I'd love to get some videos of how our boat is riding at speed. When we're light, I can feel the bottom of the engine pod slapping the water on occasion when in chop, but can't figure out the timing. I don't know if it's out of the water normally and just slapping the occasional wave it meets, or if it's coming out of the water and sapping as it re-enters! Point being, I don't believe ours is running very deep at all (when light), and can't be taking on too much water while putting around. So it would also hold true it's not taking long to empty

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                        • #13
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                          I'm taking videos of and pics while underway.. Excellent info.. I know the bottom of my POD is always below the surface while underway.. Interesting you mention this and I wonder if all the bottom of PODS should be right at the surface of the water.. Current setup leaves me light at the bow about 100LBS from stock. I removed the original wrap around seats and replaced them with front buckets on swivels (considerably lighter). So, my plan is to run the Toon to the shop, scale the Toon with a strap at the middle of the front buckets, take note of the weight, move the motor/POD forward along with the fencing and seats together until I achieve about 80 more LBS at the center of the buckets (this should compensate for the original wrap around and put me to factory default weight up front, in theory). 80LBS is about the difference between the wrap arounds and the buckets. Should be interesting to see how far forward I'll need to go to achieve this. At any rate it should be good data/read when I'm done for future projects. I'm certain engineers spent many long hours/days finding the balance sweet spot for each Pontoon and corresponding horsepower and then here we come changing the configuration nulling all their work. Sure wish I had factory specs and where the actual center of balance was for my Toon.

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