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eaglelodgemaine

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PostPosted: 19 Nov 2017, 17:52 

Joined: 11 Oct 2017, 01:49
Posts: 6
Noob here, in the dreaming/preliminary stages of building a shallow river runner to access fly spots in southwestern BC. I've been lurking for a while, and searching hasn't found me any answers.

Thanks to all the guys with jet-jon build threads, they're informative and very inspiring!

Currently, I'm running a 1969 Starcraft Offshore, which at 18ft and 2ft draft (with o/b and prop) is a bit big for the rivers I want to get to. The big tinny is nice for bigger waters, trolling in the saltchuck and other stuff. Hidden gravel bars under murky water, and small streams aren't that fun. My aluminum props have had hard lives.

The dream: 15ft aluminum bass/crappie boat with small center console, large front and rear fly casting decks, and a fraser river anchor. Mod-v hull with some V for less pounding in rougher waters.

Question #1.
What are the dimensions of a Yamaha engine and pump assy? height and length, and maybe weight and width. Yammy motor and pump because of the aluminum inlet. Haven't purchased the waverunner yet, still looking for the right deal on a recent model. Want a functional reverse bucket, modern gauge, etc. Hoping to have the engine under a flat rear casting deck. How tall are they?

Question #2.
What size/shape delta pad do I have to make for the tinny hull I haven't yet found? Tracker Grizzly mvx1648 are locally available. Yes, a bunch of cutting and welding, but I have a buddy that does sheet metal fab and TIG welding. Of course, once I buy the waverunner, I'd have a pattern to go by, but at this point, I'm still in the planning stage.

Question #3.
Build my own hull? Won't be cheaper than the Tracker 1648 MV at CAD$4500/US$3200 but at 580lbs and 7deg constant deadrise, I may be able to do lighter and have a proper mod-v with deeper deadrise at the bow for better wave entry. An 8'x20' sheet of 1/8" 5083 is about C$1400/us$1100 plus I'd have to buy my own TIG welder for a project this big, and deal with a fab shop with a large press brake to do the major structural bending.

I've been mulling over this for a while, and have started building a couple paper models in 1/12 scale to visualize the boat better. But now need dimensions. Not very many used waverunners available up here in the Great White North (tm) at reasonable prices.

See you on the water,

Brian


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PostPosted: 19 Nov 2017, 18:32 
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Joined: 27 Nov 2010, 09:36
Posts: 3922
Location: Houston, TX & Crossville, TN
I'll be interested to see if you get many responses. You are mostly asking for dimensions on a Wave Runner power plant on a tinboat site.

I'd guess that you'd find more answers on a WaveRunner site. But, there are a ton of really smart guys here who may be able to get you what you want.

Sorry, I can't help, but I am watching with interest from afar.

p.s. Just letting my old, feeble mind wander here. Other than a lack of "deck space", could one take a WaveRunner and coat the bottom with a sheet of aluminum? How would that run on the rivers up by you?



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PostPosted: 19 Nov 2017, 18:55 

Joined: 13 Nov 2014, 08:01
Posts: 526
Brian - I don't have the exact dimension you need but can give you some insight.

If you are going to be putting more than 50 hrs a year on your jet jon, I recommend considering a 4 stroke. It would cost you more, is heavier & bigger, but runs smoother, quieter, & uses about 1/3 less fuel. The prices on used VX110 are now below 3K. those engines are very reliable.

The 2 stroke engines are about 18 inches high, while the 4 stroke I recently bought is 22 inches high.

2 stroke i had was 48 inch long pump-to-front, whereas the 4 stroke is about 54 inches long.

figure about 24 inches wide either unit.

Not sure of exact weight, but 2 stroke is light enough you can lift the engine without hoist. Not so for 4 stroke.

I would look for a 16 foot or larger boat, as the engine takes up the last 1/3 of boat.

I doubt that you can build one from scratch cheaper or better than a good used boat.


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PostPosted: 25 Nov 2017, 00:26 

Joined: 11 Oct 2017, 01:49
Posts: 6
Thanks Rich,

I have thought about re-bodying a waverunner. But I'll likely just fool around with it before pulling it apart. Really want a casting deck.

Thanks Scooter,

I've been debating 2- vs 4-stroke. The more modern engines will all be 4-stroke, and give me newer instruments and everything. As for hulls, the idea of building one is too tempting. It will be fun trying to keep it from pulling while welding though. And to see how it handles when it's on the water.

See you on the water!

Brian


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PostPosted: 27 Nov 2017, 00:22 

Joined: 24 Dec 2011, 22:06
Posts: 855
Location: 72032
86tuning wrote:
Thanks Rich,

I have thought about re-bodying a waverunner. But I'll likely just fool around with it before pulling it apart. Really want a casting deck.

Thanks Scooter,

I've been debating 2- vs 4-stroke. The more modern engines will all be 4-stroke, and give me newer instruments and everything. As for hulls, the idea of building one is too tempting. It will be fun trying to keep it from pulling while welding though. And to see how it handles when it's on the water.

See you on the water!

Brian



Take a look for a Yamaha SUV 1200. Thing's as big as a jon boat, seems like I remember a guy using one to fish off of when I sold jet ski's. Bad part about a dedicated jet ski hull is draft. They draft pretty deep compared to a jon, at rest anyway. Personally for what you are doing, I'd look at a 2 stroke, the smaller/lighter the better. The old Yamaha 700's were good engines and can be hopped up a little if you wanted to go that route. The 760's were the same thing but the cylinders were different and they tended to be a little more "peaky" in terms of how power is delivered. Still pretty lightweight at around 50lbs. I have pulled many 650's, 700's, and 760's, and later on the 800's (which had power valves), 1100's and 1200's for overhauls due to (usually) water ingestion. They're all too heavy for me to pull without a lift and on some of the hulls the engine wouldn't come out without separating the cap, and I found it much easier to disassemble the engine down in the hull, then pull the long block out. Pain in the back side either way you look at it. On that note, the 4 strokes are the same way (many of them)-in that they're close to impossible to remove without partially disassembling the engine down in the hull.

The Ultra 150 Kawasaki had sort of a "V" engine in that the cylinders angled one direction and the carbs (or was it the exhaust?) stuck out the other direction. That made it a lower profile engine, but still a long 3 cylinder, and still a POJ kawasaki. I rebuilt more 750 and 900 and 1100 kawasaki engines than all other brands combined. Between the engines and the absolutely asinine trim system, they were all money pits and for that reason, I'd steer clear if it were me.

As long as the Yamaha's didn't aspirate water, they'd run nearly forever.....and cheaper to fix. BUT I've been out of the jet ski game for about 10 years now, and things have certainly changed. No, I don't miss ski's ONE BIT!!!


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PostPosted: 28 Nov 2017, 22:08 

Joined: 09 Oct 2017, 20:11
Posts: 11
welcome to the forum.
2 months ago I was in the same phase as you are. I think I watched every YouTube video that came up when I searched "jetjon". I spoke with a guy I work with who has done jetski/fourwheeler repair for 20+ yrs and the one thing he said was STAY AWAY FROM ANYTHING TIGERSHARK! If I had a bigger budget I would have went with a Yamaha 4stroke....but instead I bought 2 1995 Kawasaki 900Zxi off craigslist for 400$

lets start by looking at hull shape first.
A mod-v grizzly tracker is about as perfect as you can get in a mass produced aluminum boat for doing a jetjon build to run skinny water. IMO
YOU HAVE TO HAVE SOME FORM OF DEADRISE TO AVOID CAVITATION! Dead rise can be made by sitting the jetski hull deeper in a flat bottom aluminum boat or building a bottom with a good "spoon" in front of the intake grate. However I do not have a degree in hydrodynamics but i'm sure that whoever designed the hull for Kawasaki or Polaris or Yamaha etc.....probably did. That is one of the reasons why I went with a drop in style build for my Kawasaki powered jetjon instead of welding up my own hull or cutting a smaller hole for using a Yamaha style pump. The other reason is because of the motor and pump alignment geometry. Basically by doing a drop in style build the jetski pump and motor don't know that they are in a jon boat hull and will run as intended from the factory.

Get on YouTube and search "jet jon build" and look for the 215hp jetjon boat from Jocelyn Brochu. That IMO is one of the cleanest most functional designs I've seen.

As far as Motor and pump dimensions.....cedar covered it pretty close


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PostPosted: 30 Nov 2017, 10:22 
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Joined: 02 Jun 2015, 09:56
Posts: 281
Location: southern indiana
If I were to do one of these builds and not sure I ever would. Mostly due to time, and how much one would end up costing to be reliable, and very durable. How ever I can see the appeal of them, many have made some really good builds, but if it were me as cheap as you can find some old sport jet powered boats I would almost go with a sport jet. The yamaha ski engine/pumps seem to be the best in terms of performance and reliability, but they always seem to be pretty costly. Enough so that around me it seems a yamaha jet ski with a decent engine is usually almost as much as some of the old ski-do or various other brands of little fun boats with a sport jet. The sport jets are a pretty good engine/pump parts are pretty easy to come by, they're pretty reliable, and have been proven to push boats very well. Case in point is there are a ton of manufacturers that have and still use them as the power option in their jet sleds. SJX, Phantom, firefish, midwest jets, miracle marine, rock proof, koeffler, etc the list can go on a lot further of jet boat makers that use sport jets. Granted you won't a newer sport jet for cheap, it most likely would be an older carb model 150-175hp one, but they are still pretty good, and have plenty of umph for 16-18ft jet jon. If I built one I would start with a welded hull of some kind, and make up aluminum mount, and intake for the pump/motor. I know lot of guys just drop in the bottom of the jet ski hull, bolt/screw them down with lots of 3200 sealant. But I wouldn't want a jet boat that I would be going over logs, shoals, and rocks with a jet ski fiberglass bottom held down to a riveted thin aluminum hull with a ton of sealant and bolts/screws. I know a lot of guys have success with that, and if it works for them great, but it wouldn't be the route I go.


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PostPosted: 08 Dec 2017, 13:43 

Joined: 11 Oct 2017, 01:49
Posts: 6
turbotodd, thanks for the tips.

I may have found a reasonable deal on an older XL800. Will see how far it takes me. Would prefer a 4-stroke with EFI but they're out of my budget at the moment. First need a physical proof of concept, then may do it again in a season or two. Champagne taste, but beer budget.

I had thought about sportjets, but they're quite a bit taller from what I can see. I'm hoping to tuck everything under a low rear casting deck. The o/b on my other boat is a mercury 75 and it's great! But heavy.

Next, have to switch the MIG welder to aluminum wire and argon, then learn to weld aluminum. My paper models are beginning to look reasonable. Will go with 9-10° constant deadrise, and run the delta plate all the way forwards to the bow seam. Looks like that will make for the simplest build. Also getting a quote from a local sheet metal shop that has a 24ft press brake to do the four bends of the hull.

See you on the water!


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PostPosted: 12 Dec 2017, 19:22 

Joined: 11 Oct 2017, 01:49
Posts: 6
Not much progress yet. I've learned a few things though. Picked up a 2000 XL800 for cheap on craigslist. Has hull damage, but low hours. No signs of saltwater corrosion. Engine compression sounds even on both cylinders, and starts and revs. Engine is 2-cylinder, 2-stroke, oil injected, carbureted, and rated at 120hp. Jet has large reverse bucket and trim. Yay!

File comment: craigslist ad
25105877_10154919075821470_797350698_n.jpg
As pictured in the craigslist ad for two waverunners and trailer. Only bought one, and brought my own trailer.

File comment: hull damage
25130191_10154920604081470_54242157_o.jpg
Hull damage for your amusement.

Worst part? The 2000+ waverunners don't have the metal intake duct. The impeller size is bigger, and no factory metal duct is available. On the plus side, I've got the bigger jet with the 155mm impeller. Which means the boat will be somewhat future proof.

File comment: intake
25198639_10154920615256470_661721896_o.jpg
integrated intake duct :(

File comment: reverse bucket
25271146_10154920608921470_739564157_o.jpg
large reverse bucket, with tilt/trim

File comment: paper modelling
22404120_10154769039881470_1122677901_o.jpg
Preliminary paper model. One piece of material, three bends.

Once I sort the intake duct details, I'll save up funds for the hull material.

See you on the water.

Brian


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PostPosted: 12 Dec 2017, 21:15 

Joined: 13 Nov 2014, 08:01
Posts: 526
Does your welder have a spool gun?

If not, get one.

I threw away more wire than I burnt trying to feed thru the cable!


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