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Hi, i satart with the lake buggy plans, and end with a very diferent craft, i use a 14 ft alumacraft john boat, i start to buid the motor base and propeller protection, i use a gx420 clon 16 hp and a 42X16 wood propeller, was very unstable, i test with my dog and each time that he move, the boat move to were dogAttachment 1701Attachment 1702Attachment 1703Attachment 1706Attachment 1705
Hello and welcome to the site.. How wide is your jon boat ??? You can't move around much in my little boat while you're under way it is'nt stable either...
First, i cant delete the last picture ( please tell me how ), second, is a 36 inch on the bottom and 14 feet long , i have not another hull, will build a 4x8 or 5x10 hull to test , i dont want a dry runner, just was doing eperiments on thrust, i found that the more stables are the ones with a lenght twice as wide i measure 45 pounds of thrust with this set up, now i install a 3 blade 30 inch multiwing, also show 35 Kg at 2800 rpm´s, not sure the best prop for the direct drive on this motor. is my first visit to the forum , will keep learning, i want replace the pedal boats with small single user air propeller boats, so any reference and experience will be posted here, thanks
Welcome to the site. That boat is just too narrow to have all that weight up high like that. There is really no real way to make that one safe the way it is. You could rebuild the cage keeping it lower and as light as possible. Also keep you seating down low. There really isn't that much you can do with that boat it's just too narrow. You would be better off transferring all that over to a boat that has at least a 4 ft bottom. It won't be a runner but will get you around.
Thanks for the reference ,i agree, this was just an air drive experiment installed on a john boat hull, i do not want reduction drives and shafts, i am building a 5x9 aluminum hull, 16 inch sides and single seat ( less expensive than fiberglass ) for this engine , same one can calculate a prop size, the actual prop is a 42 X16 and was request for a 13 hp , the engine just rev to 2800 stock and the measured thrust is aroud 25 Kg, in direct drive? this to keep simple for a rental project for a public lake at the end, my idea are 5x8 hulls, 1 person, direct drive 6.5 hp ( persons below 100 pounds ), max speed 10 knots.
I'm not sure what the price difference would be between the 6.5 and a 8hp would be but I know a 8hp with a 36x24 prop works well and would be a good choice for what you are trying to to. My assumption is that you don't want the boat to get on plane and just move the boat around at a half decent speed.
Yes just to share the experience to the young people, to let them trow the pc games, the engines cost, this 420 was bought for 250, this next weekend will build the aluminum hull and i dont understand why the 16 hp are just giving 25 kg of thrust, the 6 hp on harbor freight is around 100 usd, will quote a 8 hp and try with the 4x8 for the children craft, and a 5x10 for this setup
Do you still have the governor attached?
No i remove the lever, with out the prop it rev's fine, 42 x 16 max 3200 rpm arrowprop 2 blades
If it doesn't rev to 3100 rpms with the prop on the prop is too big.
Hi, yes, dont know why other boats work fine with this pitch and diameter, 42x16 looks to be succefull on many others, i dont want a reduction drive, here is a link for a video fron today, the john boat looks to be on displacement mode all the time , here is at 2100 rpm aprox http://youtu.be/30ndMnpSCXo may be the right hull size will solve