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  • Sorry more prop questions

    I know there have been a million prop questions here lately but I am a little stumped and you guys seem to be such a good source of info. Here my situation. I have a 1974 22b with a 94 225 Johnson that is in good condition. When running the boat at wot and after some trimming I can get the engine up to about 5200 rpm and the speed is about 42-46 (depending on #people, fuel & supplies) after a few minutes of running at that speed the boat will suddenly tilt to the left and the pitch (sound) of the motor will change the rpm's will drop slightly and the boat will start to slow and I have to fight to steer it. What the heck is the story? Michigan wheel suggested a 14-3/8x21 but I am unsure about there suggestion.

    FYI

    74 22B

    94 Johnson 225

    14-1/2x19 sst omc prop

    trim tabs in the garage still in the box
    Steve Glasgow[br]Lake Worth Fl.[br]74 22B

  • #2
    I would question the 14 3/8 x 21 cxhange. Seems the WOT RPM now is just about right. 42-46 mph is respectable for that setup. When the pitch change happens, what happens first, the bow diving left or the RPM change? Does the same happen with the motor trimmed out? First thought is a motor/carberator problem. Some experts on that subject will chime in I'm sure (go get'm Dave []). If the bow dives first, you may have a motor mounting issue. Gove us some more info, more is better, and I'll throw in $.02 more.... []
    Artie Sutherland[br]Rude Attitude -\'76 Mako 25 CC. - SOLD[br]1976 Mako 21[br]2002 Yellowfin 31 - 300 hp Suzukis[br]Gulf Coast, Mississippi[br]

    Comment


    • #3
      I believe the boat tilts to the left and then the motor sound changes. When the motor is trimmed out that is when this happens it runs fine with the motor trimmed down (slower and less rpm)The bow does not dive however i fell the boat is a little on the bow heavy side while running. it is very strange when you are running at wot for a few minutes it is like you have 3 large men on board and they all moved to the left side of the boat all of a sudden. I was curious what type of set-up some of the folks with that early to mid 70's 22 and 22b are running I would be curious what prop/engine combos have been successful
      Steve Glasgow[br]Lake Worth Fl.[br]74 22B

      Comment


      • #4
        That is a strange one, if it were any boat other than a Mako I might suggest you have a "hook" in your hull. This happens when there is stringer damage from rot or a prevous accident. It would be real hard to tell on a mako because the floor is not tied directely to the stringer system. I had a boat once that eveytime the hull would flex the floor would come up in that area(aquasport). I would also look at your motor mount as Eddie suggested. the cavitation plate should be along the same plane as the bottom of the boat or withen a inch. Ive seen problems like yours when a long shaft motor was installed on a short shaft transom when you trim this package up it becomes unstable.(I believe your 22b is a 20 inch shaft aplication So you must use a 20" motor.) next time your boat is on the trailer get a couple of heavy friends to walk around inside the boat while you inspect the underside, look for any flexing of the hull. Especially in the port side rear area(I really dont think you will find any) keep us posted. dave
        [br]1994 Mako 215 Dual console Optimax 225[br]1978 Mako 19 with 90hp johnson[br]1996 Mako 22[br]1982 Mako 171 Angler 135 Black Max Mercury[br]1987 21b 225 Yamaha[br]1974 23 inboard Gusto gone.[br]1979m21 225johnson \"blue dolphin\" bought off this board and restored [br]with everyone\'s help!!Gone but not Forgotten....[br]1979 20 Mako 115 Suzuki gone[br]1977 19 Mako 115 Johnson gone[br]1976 23 Mako twin 140 Johnsons gone[br]1983 224 with closed transom and bracket[br]And 162 SOB (some other boats)[br]Venice Florida, Traverse city Mi.

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        • #5
          Gettight, I have a 1972 22' with a 1987 200hp zuki. As far as the pitch change, mine does the same once on plane. when on plane and trimmed out, there's less hull in the water, which means less resistance, which means the engine doesn't have to work as hard. Mine suzuki does the same thing. the speed will drop too, but I think that's due to my very loose lever on my throttle. I don't know johnsons too well, but could you be overheating and in turn the engine is slowing down? or possible fuel pump problem. My boat never listed to one side, but I did find a broken stringer as someone stated. Mine busted right under the fish box, on the port side, 3.5' up from the stern. Just poke your head in the bilge with a flashlight, that's how i found it. Mine is bow heavy too. I thought it was due to my girlfriend because she likes sitting in the bow when under way, but i got a new girlfriend and the boat still rides the same. So i moved the batteries back, moved the fuel cell back and it still rides the same. I'm stumped, it must just be a bow heavy boat???
          [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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          • #6
            I have checked the stringers all appears to be fine it does have a 25 in shaft motor however the transon was raised 5-6 inches to compensate. I will however check the cavitation plate in relationship to the hull. Then engine runs cool as a cucumber I have a temp gauge with sensors in each head along with a water pressure gauge and everything checks out ok. I have a feeling it is hull design that causes this and I was wondering if it can be corrected with a better set up prop size/pitch trim taps etc maybe even a stabalizer on the motor like the hydrofoil design
            Steve Glasgow[br]Lake Worth Fl.[br]74 22B

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            • #7
              I made a mistake the boat tilts to the right not the left. It tilt in the same direction of the motor rotation
              Steve Glasgow[br]Lake Worth Fl.[br]74 22B

              Comment


              • #8
                [88][88][88]

                quote:


                Mine is bow heavy too. I thought it was due to my girlfriend because she likes sitting in the bow when under way, but i got a new girlfriend and the boat still rides the same. So i moved the batteries back, moved the fuel cell back and it still rides the same. I'm stumped, it must just be a bow heavy boat???

                [:x)][(#)][][] Toooo funny.... [88][88][88]

                Listing to the right makes a little more sence. The 25" motor, as Dave suggested, in relation to the hull and the natural right hand pull may be causing this. I'd lift the engine 1 mounting hole and see how it does, then 1 more, etc. until no holes are left or it cavitates. Then drop it down again if necessary. Also, the little fin (sorry, can't remember what's it's called) behind your prop may need to be adjusted a bit. When looking at the motor from behind, try turning the back of the fin toward the starboard side.
                Artie Sutherland[br]Rude Attitude -\'76 Mako 25 CC. - SOLD[br]1976 Mako 21[br]2002 Yellowfin 31 - 300 hp Suzukis[br]Gulf Coast, Mississippi[br]

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