Which Jet Ski Motor&Pump for Boat Install?

otterbfishin

Seaman Apprentice
Joined
Dec 6, 2004
Messages
31
I've read where Jet Ski motors and pump assemblys have been sucessfully installed in small boats. They take the Jet Ski apart, cutting out the motor and pump part of the hull, and install it in the boat by cutting out an appropriate sized hole and bolting it in.<br /> I have a 10' high sided aluminum boat and I'm shopping for a used Jet Ski for the conversion. A similiar hull used a 550 Kawasaki. I think this had to do with the overall weight of the motor and jet. <br />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. I've read on this forum that older Kawasaki's have pump liner problems. Is there a Jet Ski that doesn't have such problems, or is this pretty much standard with most used Jet Skies? <br />Any help you guys could offer would be much appreciated.<br />Thanks,<br />otterbfishin
 

Jeff Walkowiak

Lieutenant Commander
Joined
Jun 23, 2004
Messages
1,944
Re: Which Jet Ski Motor&Pump for Boat Install?

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 .
 

otterbfishin

Seaman Apprentice
Joined
Dec 6, 2004
Messages
31
Re: Which Jet Ski Motor&Pump for Boat Install?

Jeff,<br />Thanks you for your cautionary comments. I will look for the Sea Doo 580. This jet ski/boat conversion has been done several times; some in alumunum hulls, some in wooden hulls providing fast and fun boating. I would like to refer you to the following websites regarding jetski/boat conversions:<br /><br />(1) http://www.glen-l.com/weblettr/webletters-7/webletter55.html#squirt-jet <br /><br />(2) http://www.glen-l.com/jetski/jetjon-index.html <br /><br />(3) http://webbjet.www9.50megs.com/index2.htm <br /><br />I realize that this is still in the experimental engineering phase of light jet boat development, but I would not be surprised to see this done commercially in the near future. 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?<br />Thanks again for the info on the Sea Doo 580,<br />otterbfishin
 

Jeff Walkowiak

Lieutenant Commander
Joined
Jun 23, 2004
Messages
1,944
Re: Which Jet Ski Motor&Pump for Boat Install?

Just save my site address because if you do this you will learn how poorly that setup will steer,and you will wish there was a way to make it steer better, that is what I do, Just finished up some stand up stuff that is totally wild. good luck with your project.
 

otterbfishin

Seaman Apprentice
Joined
Dec 6, 2004
Messages
31
Re: Which Jet Ski Motor&Pump for Boat Install?

Jeff,<br />Can you advise me of any mods I can make to improve the steering? Also, why does it steer so bad? Is it because of the added width of the hull about a 48" transom)? The conversion uses the bottom center panel of the original jet ski hull, which projects a couple inches below the boat bottom; this supposedly allows the water to feed the jet pump in a similiar manner as the original ski.e<br />For what it is worth, a friend of mine here in Talkeetna Alaska welded up a 12' aluminum hull and installed a snow machine motor and a 4" Berkley jet pump. 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). Is the jet ski pump a different configuration than a Berkley type pump? <br />FYI, I only became interested in such a project because of my friends ultralight jet boat. When I saw the "Jet Jon" rig, and I looked outside at my little 10' alum. skiff, well the idea came together. I don't have big bucks to waste on a bad project. I'm in the designing phase of another hull for duck hunting and fishing our shallow glacial rivers near my home. Sort of a combo duck boat/ river sled. Here is where I intend to spent whatever big bucks I can budget.<br />Again, Thank you Jeff for your expertise and solid comments.<br />otterbfishin
 

Jeff Walkowiak

Lieutenant Commander
Joined
Jun 23, 2004
Messages
1,944
Re: Which Jet Ski Motor&Pump for Boat Install?

To answer you simply a ski is totally different and even a birkely pump has problems especially when reducing thrust because thrust IS the only steering, I own two us patents covering 52 claims for steering mods, for jetpropelled steering improvements on watercraft. From stand up skies to jet boats , but since I own the patents and have all sorts of time and money invested in it , I don't think I would be the one to GIVE AWAY, info that would actually end up being an infringement on my own patents. LOL,, but if you ever do get it done and it steers poorly let me know and I can make you a system really inexpensively. And I do mean INEXPENSIVELY..
 

Jeff Walkowiak

Lieutenant Commander
Joined
Jun 23, 2004
Messages
1,944
Re: Which Jet Ski Motor&Pump for Boat Install?

One thing,, the hull being BELOW the original boat just dosen't seem like a good idea, I would believe it should be even with the bottom of the boat just like any jet boat would be, less drag more efficient, and water pick up is not an issue, there are many different intake grates that will handle that , but the hull is usually at a slight angle when the boat is moving anyway so I would not believe having the hull offset is the best way to do that,too much resistance and a weed catcher in my opinion.
 

otterbfishin

Seaman Apprentice
Joined
Dec 6, 2004
Messages
31
Re: Which Jet Ski Motor&Pump for Boat Install?

Jeff,<br /> It seems from all of your comments above that you would not encourage this kind of water craft project. You offer educated criticism, but not much positive help. This is an engineering project that requires help from professionals. I appreciate any help you can offer.<br /> I agree that the ski hull part should not have to stick below the boat hull (weed catcher and gravel bar bumper), but some of those who have tried the conversion thought it necessary to facilitate water intake and reduce cavitation in turns. These were using totally flat bottoms. A 5, or so, degree dead rise at the transom would go a long way towards reducing this problem, but probably not fix it altogether.<br /> I'm unsure what you mean by "problems reducing thrust". I do understand that the jet powered craft steers by power to the jet (similar to an air boat steering by power from the prop over the air rudders) and that when the power is cut back, the steering is gone until power is restored.<br /> The Berkley jet project mentioned earlier steers fine. 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. <br />I'm not a total advocate of this project, but as I said earlier, I'm very interested. I have a functional use for such a craft here in Alaska.<br />I would never ask, or expect you to give up protected information regarding this, or any engineering project. I do thank you for your offer to help with future steering problems that may arise.<br />Jeff, what kind of steering problems do you refer to above? Do you find fault with this project other than the steering?<br />Thanks for your time in responding,<br />otterbfishin
 

Jeff Walkowiak

Lieutenant Commander
Joined
Jun 23, 2004
Messages
1,944
Re: Which Jet Ski Motor&Pump for Boat Install?

Being a matter of fact type I will point out that you have stated you don't know about jet propelled watercraft, it would be easier for me to describe if you had experience with that system.There are many forums full of jet boat owners one that is most helpfull to boaters is the following www.yamahajetboaters.com ,, 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 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. 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. 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.Jet driven boats are way less efficient than a prop boat.and way more maintenance to boot.I own both types of propulsion. 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 . 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. The motor was frozen up and that would have been easy for me to rebuild, but I had no desire to bother with it.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.I love them // but mine steer, big difference.
 

otterbfishin

Seaman Apprentice
Joined
Dec 6, 2004
Messages
31
Re: Which Jet Ski Motor&Pump for Boat Install?

Jeff,<br /> You mentioned that "...Don't think you need less water for a jet than you do for a prop,..." I guess it's all where you are from. 12" of water here is a norm, not a shallow spot. A proper hull here would drift in 4 to 6 inches of water, and on step be able to skim over 2 to 3. A prop boat on the rivers here near Talkeetna, Alaska cannot be found. Not too much vegetation is such waters, but lots of sand and gravel. Shallow, gravel bottom glacial rivers flowing at up to 10 mph require jet propulsion. Only the "cheechacos" (a local native term meaning green horns) would try to run these rivers with a prop. 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. <br />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. Here, in this relatively remote area, the cheapest way is usually the best, and like you, we try to do everything possible ourselves, as the nearest town with parts is two plus hours away in good weather. A local saying is “if you ain't got it, make it". <br />I've got a 4' X 10' light weight aluminum boat hull that weighs in at about 85 lbs. A used 580 Sea Doo from the big city (Anchorage) will cost about $650 (hopefully find one with a good motor and a trashed hull). We're looking at no more than $1000 to have an ultra light jet boat, capable, because of its small size, of accessing the smaller, side waters that a larger boat can't turn around in. A commercial made boat hull with a proper jet outboard will run in at around $12,000. <br />As I said, I have a use for such a craft. 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. 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. Thank you for the yamahajetboaters site. Hopefully I'll be able to get some direct answers to questions there.<br />I am curious about this web site. Are you the only one who answers questions here? I would have hoped that other jet ski owners would have joined in to offer their two cents. Guess not?<br />My best to all you jetters in the south,<br />otterbfishin<br />Far North
 

Jeff Walkowiak

Lieutenant Commander
Joined
Jun 23, 2004
Messages
1,944
Re: Which Jet Ski Motor&Pump for Boat Install?

Being technical in nature, here is what comes to mind after you painted me a picture of what you are doing, on a plaine the boat would be ok in that shallow water, taking off will destroy it the pump is what cools the engine and here we have tons of sand if the pump is run in shallow water where sand is located the pump fills the water jackets with sand and the exhaust system and everything goes to hell in a hurry. and driving slow in a sandy bottom will also do the same thing, to eliminate the problem an intake for the jet would need to be fashioned that would draw from a position further forward to put it away from the sand, remember the intake will draw up from the bottom like a vacume cleaner, if it were further forward and angler a bit forward it may help but too far forward will prevent high speed movement as it may draw air and cavitate. all in all it will be an interesting problem to resolve. check with PWCALASKA it is a site for your local jet ski people maybe they have some help to offer you
 

otterbfishin

Seaman Apprentice
Joined
Dec 6, 2004
Messages
31
Re: Which Jet Ski Motor&Pump for Boat Install?

Jeff,<br />Thanks. Yea, the take off is always the challange.
 

otterbfishin

Seaman Apprentice
Joined
Dec 6, 2004
Messages
31
Re: Which Jet Ski Motor&Pump for Boat Install?

Jeff,<br />Thanks. Yea, the take off is always the challenge. Thus the hull requirement that it drifts in 4 to 6 inches of water, and it can be rowed to control the drift. You always try to land in an area that will be deep enough for a good take off, but sometimes you have to drift downstream a bit to find the good water.<br />The outboard jet pumps usually require shimming once or twice a season, with liner replacement always a possibility if you suck a big rock. The new stainless impellers help some, and the engineering on them is getting better. <br />I've never had a jet ski pump apart. Is it set up in a similar fashion as outboard jets, i.e. with shims that can be removed to adjust clearance as the impeller wears? Are the liners replaceable?<br />Thanks,<br />otterbfishin
 

Jeff Walkowiak

Lieutenant Commander
Joined
Jun 23, 2004
Messages
1,944
Re: Which Jet Ski Motor&Pump for Boat Install?

only sea doo has a replaceable liner as for shallow water , If there is room to do this a river may be too narrow, here is how I take off in shallow water I get on the side of my 3 seater and tip it on its side and take off in a circle as it gets up on top of the water I straighten it out and go, but a boat may be harder to put at an angle. the sand in the water jackets would be a big concern in my mind
 

kiwiguy

Seaman
Joined
Jun 8, 2002
Messages
72
Re: Which Jet Ski Motor&Pump for Boat Install?

H, otterbfishin, I have done this with a 10' aluminium dingy. Used the *** end of a 95 XP,cut it off and now have a "pod" on the rear of the boat. it is extremely quick and handles like a race car.. a whole lotta fun.. I extended the water nozzle 4" and increased the steering responce by miles. Runs a 95 720 Rotax.
 

Jeff Walkowiak

Lieutenant Commander
Joined
Jun 23, 2004
Messages
1,944
Re: Which Jet Ski Motor&Pump for Boat Install?

that would be a lot easier to do and not infringe on the inside room of the boat
 

otterbfishin

Seaman Apprentice
Joined
Dec 6, 2004
Messages
31
Re: Which Jet Ski Motor&Pump for Boat Install?

kiwiguy,<br />Do you have any pictures of the conversion? I'm VERY INTERESTED in what you did. How did you extend the water nozzle? Forgive me, but what is a 95 XP? How many CC's, Horse Power?? Would you be willing to correspond by direct e-mail?<br /><br />Jeff,<br />You're right it sounds like a real good way to go. You still have the entire inside compartment of the boat to use. Cool way to get on step - circles! In a 10' boat, it sounds feasible. Also, I saw your steering mod. Cool! Is it spring loaded so that it tips up when encountering rocks?<br /><br />kiwiguy, <br />where do you live? Sounds like Australia? How did you attach the "pod" to the hull? How long is it - how far behind the dingy does it stick to the rear? Forgive all the questions, but you are the first positive response I have had to this project. Thanks you so much for your reply!<br />otterbfishin<br />4ever1@mtaonline.net
 

Jeff Walkowiak

Lieutenant Commander
Joined
Jun 23, 2004
Messages
1,944
Re: Which Jet Ski Motor&Pump for Boat Install?

my steering doesn't need to be spring loaded nor would that be feasable, it is built not to go below the boat's plaining surface so that is not an issue, a 95 xp 720 is 85 hp all you need is a sp with a 580 the hulls are the same there is also a 650 engine made all those look the same, a 580 will do what you need but if you found any of those they will work plus attaching it at the transom requires a lot less mods on the hull. there ia a site called boat design .net that may be of some help
 

kiwiguy

Seaman
Joined
Jun 8, 2002
Messages
72
Re: Which Jet Ski Motor&Pump for Boat Install?

Hi Otterbfishin, I am currently out of the country and will be returning in about two weeks time. I will send you a few pics.
 

funpilot

Petty Officer 1st Class
Joined
May 15, 2004
Messages
358
Re: Which Jet Ski Motor&Pump for Boat Install?

Interesting thread.<br /><br />As usual, Jeff has a lot of good points and experience. Otter, the Mercury jet pumps I'm familiar with don't shim like the outboards do. They basically are an L-drive, and everything Jeff says about sucking sand or rocks at low speed is true. That said, a purpose built jet boat like the 10 year old Mirage I own can be had for under $4,000 from someone who is tired of the fuel consumption.<br /><br />As for wear ring (jet pump impeller to ring clearance) damage or wear from debris, some of us have successfully applied JB Weld to our inner annulus allowing the impeller (hard stainless steel) to smooth the ring in as we tighten it onto the pump. Seems to work for quite a while, and clearance numbers are exceptional.<br /><br />The drift and start idea is a new one to me, I wish I had heard of it before I grabbed a chunk of granite right up my intake on my first river excursion!<br /><br />Welcome to Iboats.<br />funpilot
 
Top