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1978 mako 25 rebuild

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  • #46
    Hey sailor ! I added apx 3.5”-4” of height to the floor.. Plan for motors is to go with New twin 200 Suzuki’s. there weight is right at 1000lbs, The tub on the bracket isn’t as big On the stainless marine bracket as an Armstrong that’s for sure. I moved the gas tank forward about 2’ from factory. After doing rigging tubes today Today, made a minor change in the plan making a customer 20 gallons water tank which will go all the way in the bow an The water tank I had made is going to be an aux 40gal has tank.
    The 140gal main tank just didn’t do it for me. With the added 40gal I’ll have the capability of having 180gallons of fuel on board

    planning to do a float test an simulate full load to check water line an how it sits in the water.

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    • #47
      My tank builder decided my crazy idea to put the water tank in the tiny bow cubby was just nuts... his idea 2 rectangles between main an chime stringer 20gallons each total of 40gallons so Gained more fresh water the the bow area... was able to lay some more gel down in bow storage(have the time while waiting outa make it look pretty too) inching closer to getting the floor in 🧎🤞 Hoping a few more good wrk weekends an we can get it glued down

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      • #48
        My 25 is pretty bow heavy as stock. So you moving the fuel cell forward + adding 350# of water to the bow would be a bit much, I'd think?
        [br]Michael R. Delgado[br]1972 Mako 22[br]http://classicmako.com/forum/topic.asp?TOPIC_ID=15745[br]1976 Mako 25[br]http://classicmako.com/forum/topic.asp?TOPIC_ID=18013&SearchTerms=mako,25[br]

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        • #49
          I believe Mike is right. I removed both the original tanks (40 gal front and 80 gal rear) and replaced them with a single 80 gal tank in the front of the coffin. With a full tank she sits fine. But, at idle speeds into a 6 knot current I can feel the bow grabbing a little more water than I'd like. Up on plane she acts fine. Once the fuel gets down to about 50 gal she acts fine at idle into the current and also gets her balance back the way she was originally.

          My engines are transom mounted and total 820 lbs. Completely different configuration than your planning, but maybe this info helps. Good luck and keep up the good work.

          BTW. If I were to do it again I would go back to two tanks because of the ability to manage weight distribution.
          Last edited by flounder; 09-29-2020, 05:57 AM.
          Ole Joe
          Just floundering around
          White Hall & Ocean City, Maryland
          1978 Mako 25

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          • #50
            Thank you guys that’s the great feed back I like and sure do appreciate it, the weight distribution is deff a concerned mine,
            i had a feller do a drawing of the hull an kinda of give me the best area for the hulls center of gravity an this is what he sent and what I went by. I since Nix’d the fronts storage areas. Ended up using the full 90” for tank area, so the main fuel tank an planned water tanks (now aux fuel tank)are only separated by a bulk head which I believe it’s 48”-50” off the transom not the full 59” I will double check.. planning to do 2 Suzuki 200’s which are roughly 1000lb. The console an T-top is hoping to get is around 1100lbs.. so ya a lil concerned on being bow heavy.. still wana do a sitting still water test an get the water line an see how it sits in the water.

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            • #51
              I always think about doing the bracket and messing with the center of gravity of the boat. I racked my brain, thinking, do I cut out the bulkhead forward of the tank and slide it forward? water tanks? And my problem with figuring this out is the water tank and fuel tank is a constantly changing variable. The tanks can be full, half full, empty, so you can't accurately calculate this.

              I'm not an engineer, so I would launch the boat with engines mounted and put sand bags or lead in the bow until the ride felt right.

              Curious, why will your T-top and console be so heavy? I weighed my t-top project and the hardtop was 140#, frame was 40#. Regardless, that will be in the center of the boat and not really a factor.

              Anywho, nice work! keep plugging away.
              [br]Michael R. Delgado[br]1972 Mako 22[br]http://classicmako.com/forum/topic.asp?TOPIC_ID=15745[br]1976 Mako 25[br]http://classicmako.com/forum/topic.asp?TOPIC_ID=18013&SearchTerms=mako,25[br]

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              • z28joe2
                z28joe2 commented
                Editing a comment
                im 100% not an engineer..... well maybe some redneck engineering thrown in the mix lol
                the console I'm trying to get is the whaler dauntess 270 whaler as well as frame and t-top I'm going off there numbers from a source at the plant, there
                t-top alone weights 500lbs console is apx 400-450lb an estimating the frame to be apx 150lb or more (original plan was the edgewaters 260 but that fell tru)

                you are correct on launch the boat with sand bags an weight...we're going to get rain barrels an fill them with water an try an calculate as much as possible, just ain't had all the stars aline for the perfect week day off wrk to do so and not a chance around here to be near a boat ramp for testing purposing on a weekend till the few colder days a year we get

            • #52
              Above post:
              Originally posted by mrdelgado View Post
              so I would launch the boat with engines mounted and put sand bags or lead in the bow until the ride felt right
              Emphasis on "until the ride felt right" ....So true.

              I used a program ( https://microship.com/balance-your-b...vity-database/ ) to assist me in figuring out where to place my new tank. By comparing the original weights of the hull, dual tanks, and twin 2 strokes versus proposed hull, single tank, and twin 4 strokes I was able to get an idea of how much the balance was being shifted. It helped, but did not tell the full story. Getting the center of balance right does not seem to be strickly a math calculation. The builders work it out using hull prototypes and mold modifications until they've got it right.

              There are a couple things that I would do if it was my project. One, I'd split the 140 gallon tank in two thereby shortening the length of weight transfer and allowing for fuel management that can improve the balance as needed with different trips and loads. Two, I probably not add the water tank, especially not up front. Three, I'd definately do what Mike suggested, test runs.

              After you spend as much time and money as you will be, you sure wanna be right.

              Ole Joe
              Just floundering around
              White Hall & Ocean City, Maryland
              1978 Mako 25

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              • #53
                Originally posted by flounder View Post
                Above post:


                After you spend as much time and money as you will be, you sure wanna be right.

                you are 100% correct on time an money spent to want it to be perfect... if it want for the missed the only water tank on board would be water bottles.. reasoning behind the 2 virs just one was to balance weight, may not be a bad idea to cut them back to 10gal each to have less bow weight, im sure they will rarely be used.. but got please the misses or else well im sure every one knows how that goes, i like that program you have in your link i can see me spending quite a bit of time at the computer messing around with that!!

                on an better note weather is going to cool an clear all weekend here in FL so i see a solid weekend of boat work in the future to make some more forward progress again
                thank you all for input and feed back an hopefully ill have some updated photos on Sunday for everyone.

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                • #54
                  Originally posted by z28joe2 View Post


                  the console I'm trying to get is the whaler dauntess 270 whaler as well as frame and t-top I'm going off there numbers from a source at the plant, there
                  t-top alone weights 500lbs console is apx 400-450lb an estimating the frame to be apx 150lb or more (original plan was the edgewaters 260 but that fell tru)
                  That's really heavy for a t-top! I'd be a little worried about having all that weight so high up. That might really affect the stability of the boat...

                  Toronto, Canada
                  76 Mako 23
                  https://forum.classicmako.com/forum/...t-s-23-rebuild

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                  • #55
                    Water tanks are finally done!! Been sitting in limbo till they came, got them coated this morning used truck bed liner since there just water tanks. Going to shoot for getting them plumbed an foamed in tomorrow

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                    • #56
                      I like your idea of the water tanks. I keep my boat on a mooring during the summer and am in the process of putting a tank in the forward bilge. I replaced my 2 fuel tanks with a single 130 gallon tank and converted the second fuel fill and vent to supply the tank in the forward bilge area. I can fit two five gallon tanks in there plummed together. I just want enough water to flush the motor since I am on a mooring. If I ever have to cut up my floor I am totally stealing your idea! I agree with the other guys that the boat feels a little bow heavy at times, especially since I have a single engine. I would keep them as far back as you can.

                      Current
                      '76 Mako 25 w/ '03 300 Yamaha HPDI
                      Previous
                      '85 Mako 21B w/ '94 225 yamaha
                      '73 Mako 19 w/ '96 112spl Evinrude
                      Brick, NJ

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                      • #57
                        Water tanks are plumbed ✔️
                        Rigging tubes all in place. an finalized✔️
                        installed anchor locker drain✔️
                        was able to foam in water tanks, an all area of the bow,
                        we would of gotten floor glued in place today but the Florida wet weather decided that I was not going to be able to do that as the rain moved in! Hopeing to get an good evening during the week to glue floor... Everyone says it a boat if floors in

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