Jet Jon Build Pics ...VIDEOS LINKED!!!!!!

[bulldog]

Looking great so far. Clean and professional. Keep up the good work.

 

[majkowskid]

UPDATE 9/27!

99% DONE! just waiting on the fuel tank to come in the mail! throttle successfully installed yesterday, and works PERFECT. all electrical except for trolling motor wiring complete, key ignition installed, and console built. (console is not complete together in these pics. coverings are just laying in place. not secured down yet because of wiring to be completed)

runs GREAT. can't wait to get it on the water! hopefully next week!

 

[PSG-1]

It's looking good! You should be able to access some narrow and shallow areas with a boat that size!

 

[Billvsthefish]

Thats a sharp looking boat you got there. I also like your seating arrangements. Its gonna be lots of fun.

 

[fender66]

Turned out great. Love to see some video of it running. :wink:

 

[majkowskid]

once i get the fuel tank in, i'll be sure to take a video of it on the water

 

[majkowskid]

man, what a pain in the butt getting this thing registered in texas!

had to transfer the boat title into my name... fine. i understand.
had to transfer JETSKI that engine came out of into my name, even though jetski is destroyed... ok, kinda understand.
had to then fill out affadavit for jetski being destroyed. then, when new title gets to me in my name, i have to surrender it to the TPWD. wtf?
then, i had to pay for a NEW title, utilizing the old boat's HIN, but showing that it's a homebuilt boat. shows "inboard" powered now.

total cost = 1 ARM 1 LEG.

rediculous.

that being said, the TPWD guys are awesome. really nice. front desk clerk called out a couple wardens and a lake patrol guy to look at my creation.
Lake patrol officer wants to "run me" in their lake boat, which is a 18 foot center console with a 150 hp outboard. he says it'll run 42 mph supposedly. hmmm... wouldn't it be nice to smoke the lake patrol in a 13' jon boat???

 

[fender66]

Lake patrol officer wants to "run me" in their lake boat, which is a 18 foot center console with a 150 hp outboard. he says it'll run 42 mph supposedly. hmmm... wouldn't it be nice to smoke the lake patrol in a 13' jon boat???

Never happens if we don't have a video to watch. :LOL2:

 

[PSG-1]

Sounds almost like my fiasco with the Aluma-Jet.

The story behind my boat goes back a ways. Before I acquired it, someone had brought it to me to give them a price to fix the extensive corrosion on the bottom. I told them it would be in excess of 500 dollars, and they balked at the price.

At some point, they traded it in to a marine dealer when they got a new boat. Some time after that, the marine dealer took it to another welder, wanting a price to fix the corrosion. He told them about the same thing I told them....roughly 8 hours of labor at 75 dollars an hour. So, once again, it was put in storage.

A few years later, that marine dealer went out of business, and they pretty much gave the boat to the other welder, who had done a lot of work for them in the past.

A couple more years passed, and the other welder went out of business, and moved all of his equipment out to his property where he lived. Not long after that, he was selling that property, so, he had to get rid of a lot of the stuff he had stored out there, and I went out there to see what I could buy.

I came home with a good assortment of aluminum and stainless, as well as paying 50 dollars for that DuraCraft. I initially planned to cut all the ribs out of it, and anything else I could use for repairing other boats.

But, as I looked at it, I saw that the corrosion was primarily on the center V, and I knew I could fix it, so I did.

Well, I ran into an issue when I went to title it. When I bought it, I was told that it had no title, but since I planned to use it for scrap, I didn't really need one. The hull ID tag had been removed. So, I had to contact SCDNR. I sent them photos of the boat, and told them what I had done. They sent a marine investigator out to see what he could determine. He came out, and found the alternate hull ID number (boats always have 2) He wrote me and the seller a warning ticket for selling/purchasing a watercraft without a title. He said because I had not tried to turn around and sell the boat for profit, that it would just be a warning ticket. He said that he would run the number, and as long as it wasn't stolen, they could issue a title for it.

It took a couple of months, but they were able to re-issue the title, even with the same registration numbers (I guess the same registration number stays with the hull as long as it's in the same state)

So, long story short, I got it titled. Although I filled out the paperwork and listed it as an inboard engine with jet propulsion, my registration still lists it as an outboard. LOL


Not sure about being able to outrun the game wardens' boats.....but I can tell you that game wardens have been aboard my boat several times, when I have taken them out on the water to write tickets to natural resource violators that I have witnessed, such as illegal duck hunting within the state park, poachers robbing crab pots, people harvesting shellfish from polluted areas, or at night, and numerous other violations. There's probably been at least 200 tickets/cases made from aboard that boat.

They pretty much understand that I know the creeks around here better than they do, especially at low tide, and that my boat can get into areas that their patrol boats can not. The guys in SCDNR do a helluva job, but they also cannot be everywhere at once. Concerned, observant citizens are the bulwark of a conservation officer's arsenal of resources in the fight against violators.

 

[Anonymous]

majkowskid, where is this rig going to be fishing out of?

It's looking good! You should be able to access some narrow and shallow areas with a boat that size!

 

[majkowskid]

we have 2 local lakes. one is dang near dry, but there's some nice areas left that are too shallow for props. the other lake is small and is basically kept at a constant level. (by draining the other lake!) it's got some nice inlets and such as well i'd like to sneak around in. why do you ask?

 

[majkowskid]

TODAY WAS THE FIRST TEST RUN!

I need some help though to all whom have built one of these. please look at my pics in my first post to reference bottom of boat.

i'm having MAJOR cavitation issues. like BIG TIME.

on perfectly flat water, i hit 41 mph via gps. if there is ANY waves, it starts sucking air majorly. water has to be like glass for it not to happen.

i'm thinking its mostly from the ribs that are on the bottom of the boat. these are structurely important as the boat hull is thin, but i'm wondering if i can cut "gills" into it to help direct water from outside the ribs to inside them... besides that i don't know what to try. i already have the spoon idea going, but i'm guessing i didn't construct it the right way. i seriously think 99% of it is from the ribs though.

if anyone has any suggestions (ranchero50) i'd appreciate it! someone told me about an intake grate that has a scoop built into it that would probably help... worth a shot??

 

[Ranchero50]

I think you are screwed... :shock:

How about a picture showing you sitting on it in the water, maybe a couple decent pictures from the side without the background blotted out so we can have some perspective.

As a guess I think your intake is too far forward for the length of hull, you are sitting too far aft and at higher speeds in chop even the spoon is coming out of the water as the hull planes on the ride plate under the nozzle. Only real fix is more weight forward to keep the nose down. Again, some pics or video of it in action will help troubleshoot or eliminate a lot of variables.

Mine will cavitate in too heavy chop as well but I don't run it that hard because of the hull pounding.

Jamie

 

[majkowskid]

Ranchero.

Thanks a lot for the response!

We took a video on my buddy's phone and we're working on getting it uploaded.

I'm pretty sure that it's not a weight issue. It actually ran BETTER with only two people in the boat, than with a third sitting up front. (37 mph with 3 people in it, but it had to be STILL water).

what's funny is that it actually runs better with the nose sticking up out of the water (before it planes up) than it does on plane in any type of chop.

do you not think it could be from the ribs on the bottom of the boat that are in this pic?
or is my spoon area not right?

this is what i was trying to explain about cutting some slits in the ribs to direct water to the pump... also thought maybe one of the higher end intake grates with the scoop on it may help keep the pump loaded?

 

[majkowskid]

oh, and sorry about the pics.... i will update with some more. i built the boat in my buddy's garage (he had more room at the time) and he didn't want pictures of all stuff all over the internet, so he made my blot them out.


i'll take some pictures either today or tomorrow showing the complete profile. the intake is actually WAY far back on the boat. i'm not too sure about the theory about the pump sticking out of the water... as i said above, when it's and 1/4 throttle, before it planes up, it actually doesn't cavitate at all. even on glass water... and i mean GLASS it still cavitates a bit. it's almost like the "tunnel" area created by the ribs is keeping any water from the sides from being sucked into the grate.

 

[lovedr79]

Have u thought about a top loader grate and an extended ride plate? Possibly change the impellar to a different pitch

 

[majkowskid]

lookin into the intake grate as we speak... impeller i didn't think of. what's the purpose of the ride plate? how would that affect the intake?

 

[Ranchero50]

That you've gotten it to go over 20mph is more than most guys get. That it runs up to 40mph on flat calm says the pump is staying loaded (everything is working) at that speed so I don't think a load grate will help much but if you find one cheap it can't hurt to try it out. Load grates work by forcing the water around the curve of the inlet roof when the hull is going to fast for the water to naturally bend without cavitating along the roof. At 40 you aren't that fast.

That you are cavitating at speed in chop tells me that your pump isn't drawing air free water in that chop (seems basic enough right?) so I would try to get the hull to draw air free water vs. just more water.

Cutting the strakes as drawn I don't think will do anything except make it worse. If anything I would look at cuttng them the other way to allow air to escape from the centerline. What concerns me is I don't know what will happen to the water under the center of the hull at speed if it's being vented out the side with the air. Possibly less pressure causing more cavitation, possibly more more planing effect on the outer section of the hull.

I think what you can do that will make the most effect is lower the middle of the spoon so it draws from deeper, less aerated water. My spoon draws @ 1.5" deeper than the strakes run, in chop I have to get the kid to lean over the bow to minimise the cavitation. Simplest test would be screw on a couple 4" wide sections of luan (5mm plywood) to get a profile and then body putty over them and play with it.

Now that it's together you get to make it run right. Kind of why mine still isn't finished
Jamie

 

[PSG-1]

Have u thought about a top loader grate and an extended ride plate? Possibly change the impellar to a different pitch

Good suggestion. I was about to suggest the same thing. A top loader grate will feed more water to the pump, to keep it from starving out and cavitating, even at 40 MPH.

Shifting more weight to the rear will also help, it will sink the pump a little lower in the water, but you may need trim tabs to offset and prevent porpoising. He did say that it ran better without a person in the bow, with the bow being up some, so that tells me that putting weight on the stern, theoretically, should work.

Also, try a "Concord" or 'swirl' impeller, rather than a straight rake profile. The swirl impellers are a little more forgiving of cavitation.

If you're running a progressive pitch impeller, such as a 13/19, you may even need to have the pitch modified, maybe to something like a 14/16. Again, this is one of those variables that you have to experiment with.

 

[Billvsthefish]

I've been following your build. I think you need a more defined spoon. With a flattie, air and water go straight back. I think you need something to disperse the air, or redirect it rather. I had your same problem, and i built a spoon (Ranchero's idea). It took away 99% of my cavitaion. But i do have an aftermarket intake and ride plate, but even with these i still had cavitation. Take a look at my spoon, it definately works. Bill
https://www.tinboats.net/forum/viewtopic.php?f=21&t=21899