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Thread: New jon boat for Merc 25hp prop.

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    Default New jon boat for Merc 25hp prop.

    Looking at maybe getting a new jon boat and mating it with my current motor Merc 25hp two stroke prop at 112lbs. I have it on a Seaark 1448 riveted flat jon now at 245lbs. I can get 4 men on plane and run at good speed, but need to run shallower. Looking at either an Alweld 1648 flat or 1552 with prop tunnel. Both boats are listed at 355lbs. .100" hull. I was looking at a Yamaha 40/30 jet but not sure if a jet would do in our river, it tends to have debris from time to time. Don't want to go any heavier on the hull either, lots of spots where we have to drag the boat. Do you guys think the prop tunnel would gain me much clearance on the prop, or should I just stick with the non tunnel? I've read with a prop tunnel I would need a jack plate and also probably a different pitch prop with more cup. I really just hate to change motors, this little motor is a powerhouse.

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    Not really sure how a tunnel will help you, but have you ever thought about putting on a rock hopper on your motor and maybe a Jackass lift or transom lift to putz across shallow water and once your on step, you can also lift your motor to run shallow. I had a 18' Jetcraft with a Hydraulic Transom lift and once I got on step I would raise my motor up to run in shallower water. Worked great. I know what you mean about that 25 merc. I have an 1972 20hp merc that pushes a 14' hewescraft river runner and that little boat flys.

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    Quote Originally Posted by Tbradley View Post
    Looking at maybe getting a new jon boat and mating it with my current motor Merc 25hp two stroke prop at 112lbs. I have it on a Seaark 1448 riveted flat jon now at 245lbs. I can get 4 men on plane and run at good speed, but need to run shallower. Looking at either an Alweld 1648 flat or 1552 with prop tunnel. Both boats are listed at 355lbs. .100" hull. I was looking at a Yamaha 40/30 jet but not sure if a jet would do in our river, it tends to have debris from time to time. Don't want to go any heavier on the hull either, lots of spots where we have to drag the boat. Do you guys think the prop tunnel would gain me much clearance on the prop, or should I just stick with the non tunnel? I've read with a prop tunnel I would need a jack plate and also probably a different pitch prop with more cup. I really just hate to change motors, this little motor is a powerhouse.
    All those reasons make it evident that a jet would be to your advantage. A 1648 with a 60/40 jet would scoot along very nicely, had a setup like that for several years and I really enjoyed it. I carried a number of moose out with that boat.

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    Quote Originally Posted by chico99645 View Post
    Not really sure how a tunnel will help you, but have you ever thought about putting on a rock hopper on your motor and maybe a Jackass lift or transom lift to putz across shallow water and once your on step, you can also lift your motor to run shallow. I had a 18' Jetcraft with a Hydraulic Transom lift and once I got on step I would raise my motor up to run in shallower water. Worked great. I know what you mean about that 25 merc. I have an 1972 20hp merc that pushes a 14' hewescraft river runner and that little boat flys.
    Well I was thinking with a prop tunnel I could add a jack plate that would allow me to raise the motor even higher when in the shallows. I think prop tunnels are generally around 5" tall, so I could gain that much clearance when on plane. Chico you didn't have a prop tunnel when running your jack plate? If not how high could you raise the motor and still not have cavatation problems?

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    I didn't have a prop tunnel. It was an 18' Jetcraft 1825 Kokanne. Once I got on step, I could get my motor up 3-4 inches with no problem, Tried once to come up all the way, and it did cavitate. Its kinda hard to see exactly how high you did lift your motor as there is not really a guage to look at. I know, it was a great investment and was also a great selling point on my boat over others when the craiglist market was flooded in March.

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    Just pulled the trigger on one of these electric jack plates http://tsgcustom.com/default.aspx. Hopefully it will help in my situtation. You can mount the plate so the cavatation plate is 2" from the bottom of the boat when the jack is all the way down, then have 4.25" more travel with the jack plate. One of the good things it only weights 15lbs.

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    Been away for a while, so now back to the boat. I now thinking I would like to have something in these ranges Alweld flat bottom, 1648, 1652 or 1748. The 25 hp prop merc does really well with the 48" bottom I have now, and I don't know if going to the 52" would slow me down some. I do know that going to a 16' or 17' would perform better than the 14' I have now, just not sure about the bottom width. So what do you guys think, 48" or 52".

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    My G3 1848 scoots along nicely with a 15hp prop carrying 3 adults and a 60# dog and gear for the weekend. In fact it'll outperform an equally powered 14' or 16' boat (of equal hull width and proportional hull weight) that has anything close to a similar load, including empty. Hull weight is a big deal in your search. I had an 18' x 60" Wooldridge with a 200hp on it and loved it yet my G3 works great with a 15hp. There's a lot of difference in 18' hulls, even when you limit the search to jon boats. Compare a Sea Ark to my light G3 and you'll see what I mean.

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    Quote Originally Posted by Mr. Pid View Post
    Hull weight is a big deal in your search. I had an 18' x 60" Wooldridge with a 200hp on it and loved it yet my G3 works great with a 15hp. There's a lot of difference in 18' hulls, even when you limit the search to jon boats. Compare a Sea Ark to my light G3 and you'll see what I mean.
    Yes, hull weight is the big deal. How much does your G3 weight? I know most of the 1648 riveted jons if looked at weight in around 275lbs. The Alweld 1648 is 355lbs, but at .100". I don't necessarily need .100", but I do like how Alwelds are built.

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