I then mapped out where I wanted to cut and removed all the parts I did not want, removed the floor and stringer etc and started building the boat from the ground up, this was to accomodate a fishing boat with no obstructions in the center of the boat, fuel tank compartment anchor compartment console with steering wheel depth finder built in battery box for 2 marine batteries a casting platform and a removable front seat for a passenger when needed, no slip floor and casting deck surfaces and a jack plate with a 35 mercury ob on it, plus a trolling motor, battery switch in line water seperator, multiple pole holders and side cargo nets to hold thing from blowing around,bait well, internal flourescent lighting for fishing at night, and a few other tricks, this boat will do 32 mph loaded up with just me in it and take the rough water in a storm. These Sea Doo models are designed to fill the needs of high performance enthusiasts who crave adrenaline rushes, power and handling in a SeaDoo certain to be noticed on and off the water. I don't have big bucks to waste on a bad project. I've read on this forum that older Kawasaki's have pump liner problems. Also, that motor will not live long running at about 8000 rpms. The Sea Doo is powered by either 2 stroke or the 4 stroke engine. Don't think you need less water for a jet than you do for a prop, to take off you need about the same, the jet is a big vacume cleaner and will suck up the bottom when you take off in shallow water, or if you go slow, and you need to jump in the water and clean out the intake if you get plugged up.
The thing went like a bat out of hell and had no steering problem did have other problems, but steering was not one of them. Runs a 95 720 Rotax. These were using totally flat bottoms. I appreciate any help you can offer. Here is where I intend to spent whatever big bucks I can budget. Usually had them about 7500 rpm's with twin pipes and 48mm carbs. Well I adjusted carb yesterday and got it to quit backfiring and as u hit throttle it would take a deep breath than rev I cured both those issues and timed it again rotary valve, and now today it will turn over and keep trying to start but won't start up, plenty fuel,plenty compression,plenty spark, what the heck is this skis issue,.
I was leaning towards turing my 05 rev 440 into the Triple 809 motor with the kit threw Bondi, but I would like to do something different! If it were a jet boat and it had a 80 hp engine it would probably go low 30's tops, would take a lot longer to plane and use 4 times the gas, plus I would be dealing with weeds in the intake grate constantly, That is why I would not bother. Hopefully I'll be able to get some direct answers to questions there. As I said, I have a use for such a craft. This small boat could slide up into the side sloughs that the silver salmon choose to spawn in, and the ducks drop in to hang out in. It is a good motor but don't know how it would work in the sleds.
I would never ask, or expect you to give up protected information regarding this, or any engineering project. I own jet skis because they are to boating what motorcycles are to the auto industry, with one big difference unfortunately, gas consumption, I burn about 25 gal per day playing with my jet skis, and more if we are waterskiing behind them. It actually ran well so I ran it on the hose for a little while to burn off any remaining water. I think this had to do with the overall weight of the motor and jet. After that I cut the hull up and removed all the parts to sell.
We use these light weight jet ski Sea Doo pistons for 20+ years with no problems in our race engines. I am very intrigued by these conversions, and since I already have the boat hull, why not drop a jet ski in it and have some fun? Having zero experience with Jet Skis I would really like to know from Jet Ski owners and operators, which Jet Ski would be the best for this project. Jeff, Can you advise me of any mods I can make to improve the steering? The motor was frozen up and that would have been easy for me to rebuild, but I had no desire to bother with it. We've got some of the best rainbow trout and salmon fishing in the world, not to mention the fall duck hunting, as the ducks come here to breed before flying south to you all. First installing a fiberglass hull from a ski in to an aluminum boat is probably a real bad idea, I have built numerous boats and I would not even attempt it as it would brobably be a big expensive failure, a fiberglass hull would be a different story,, as for making a jet boat from a jet ski, jet ski or jet propelled watercraft are quite inefficient, as a rule and expensive to operate, but perhaps a sea doo 580 set up would be the least expensive and most readily available for that.
Jeff, It seems from all of your comments above that you would not encourage this kind of water craft project. We have the latest SeaDoo jet models with specs, parts, accessories and info. Jet driven boats are way less efficient than a prop boat. Strong engine, I was wondering if anyone had info on this at all! Sea doo made an inflateable driven by a 580 and a 650 neat toy but not popular, I just had a guy offer one to me for free to haul it off his property trailer and all and I said no thanks. Jeff, Thanks you for your cautionary comments.
I did say that I'm very unfamiliar with jet skies, but I have twenty-five years of running these rivers with jet outboards and air boats. And is it even possible? Not too much vegetation is such waters, but lots of sand and gravel. You wouldn't get two miles before the prop looked like a twisted potatoe chip that includes stainless props , even if you installed a hand operated motor lift sizzor type , which was the only way to get around before water jet propulsion came to this area about 35 years ago. I'm not a total advocate of this project, but as I said earlier, I'm very interested. You offer educated criticism, but not much positive help.
Again, Thank you Jeff for your expertise and solid comments. Jeff, what kind of steering problems do you refer to above? I own both types of propulsion. And it wtill runs as strong as the day it was born and never a rebuild- amazingly durable! This is an engineering project that requires help from professionals. The Berkley jet project mentioned earlier steers fine. There are many forums full of jet boat owners one that is most helpfull to boaters is the following ,, I have a lot of experience with jet propelled water craft and if I were doing this and I honestly would not waste my time or money, not criticism at all, just an honest fact,I would do it differently, actually there are many inexpensive jet boats around, and they are already set up,, a conversion will get costley and not be practical , I built a 14 foot fishing boat , I looked for an old runabout and found a 1958 hull this was super heavy ,really thick fiberglass. I would have hoped that other jet ski owners would have joined in to offer their two cents.
I have a functional use for such a craft here in Alaska. Sea Doo offers a 2 seat, 3 seat and SportBoat model in the Sea Doo line up. The new stainless impellers help some, and the engineering on them is getting better. Note: Does not come with rod needle bearings. The battery was dead and the cylinders puked out water once I put a fresh battery in and cranked it. The main criticism of the steering by those who have done the conversion is that it tends to cavitate in sharp turns, as do many jet outboard powered craft. I really believe it was on this forum but I could be wrong.
Thus the hull requirement that it drifts in 4 to 6 inches of water, and it can be rowed to control the drift. Any help would be great! I do thank you for your offer to help with future steering problems that may arise. I spent a lot of money building it and I have used it for years, I would never dream of retrofitting a jet drive to it, I can shoot flats wot in 12 inches of water, I can go in 8 in with the trolling motor, and I can use it all day on a 6 gal fuel tank with plenty left over. A similiar hull used a 550 Kawasaki. I haven't had the pipe off but thats the way it looks.