Botswana 2072 160HP Outback

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okavango

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Maun Botswana
Inspired by this great forum I started building a 2072 Outback by Aliboats Botswana powered by a Yamaha 160Hp HO engine.
One year later and I am getting close to putting a bare bones hull on the water to test the concept
 

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Mighty fine work there! If you have any questions about the FXHO engine, let me know, since this is the same engine I used in my boat.

Especially as it pertains to wiring, as I ran into the issue of the tech manuals and my harness color coding not being the same, and it was a PITA to figure it out. If your engine came out of a Yamaha jet boat, you'll find that the wiring harness may have quite a few more wires than what you'd expect. If so, 2 of them are for the no-wake mode, and 3 of them are for warning indicator lights. The rest are for start/stop, tach, ground, and ignition. And then the 2 wires for the electric fuel pump.

Also, whether it came out of a boat, or a PWC, you'll find a 3-wire plug that is separate from the main plug. This is for the YDS (diagnostic system) You can buy the software and the adapter cord, and run diagnostics on the engine with a laptop computer (windows only, no mac) YDS will show engine hours and many other data points.

Once you get it on the water, I can say with confidence that you will really like the FXHO engine. It's quiet, powerful, and has good fuel economy at moderate cruising speeds, I burn about 3-4 GPH at 30 MPH in my boat.
 
Thanks PSG
Read through your build in great detail for much inspiration and many good ideas, thank you for sharing all your posts.
The engine and pump are from a PWC and were tested before I parted it out, all good with 38 hrs recorded, but would like to check that with the YDS. The rest of the harness appears to be plug and play, hopefully?
Still not sure how this large hull will perform, but aim to keep it light and test performance before adding all the finishing touches also not overly sure about the PWC reverse bucket.
Will most likely temporarily install the Jet Ski controls for the test run.
 
I don't think the large hull will affect you too much. Remember that these engines are also used in 23 ft wake boarding jet boats. Granted, there are 2 engines in those boats, but consider how much heavier that fiberglass hull is than your aluminum hull. My setup weighs about 1200 lbs, with a 48 in beam, and about 12 ft in the waterline.

If you still have the factory controls, it will be plug and play, unless you want to extend your harness, then just make sure to splice the wires one at a time when you're adding in the extra run, so you can keep track of which is which.

My engine, harness, and ECM came out of a boat, and I did not have any factory controls. I had to do a lot of figuring and modifying to fit my existing harness. In fact, I'm using the tachometer from an AR-230 jet boat. It uses an 8-pin plug, which I was unable to find, but was able to make my own pin connectors and then sealed it with marine grade silicone. Works just as good as a plug.

As for the reverse bucket, it should do OK. I'm using an XL1200 pump in my boat, which has a very small reverse bucket, compared to the newer Yamaha 4 strokes. Still, it's ample enough for my application. If you're going to use a reverse bucket off a Yamaha FXHO, that should be more than enough. I say that because we own a VX110 Yamaha, and if I let off the throttle at 20 MPH, hit the reverse bucket, and then hit the throttle, the bow of the jet ski will do an instant nose-dive, and it will almost put me over the handlebars. It's the same reverse setup on the FXHO as the VX110 and FX140.
 
I think it should scoot along pretty well. Narrow hull will act like a destroyer and should cut pretty well. I'm wondering if it wouldn't like a couple guide strakes further forward though. Testing should show if it turns lazily.

Stomp grate to avoid swimming with the croc's? Good idea. =D>
 
PSG-1 said:
I don't think the large hull will affect you too much. Remember that these engines are also used in 23 ft wake boarding jet boats. Granted, there are 2 engines in those boats, but consider how much heavier that fiberglass hull is than your aluminum hull. My setup weighs about 1200 lbs, with a 48 in beam, and about 12 ft in the waterline.

If you still have the factory controls, it will be plug and play, unless you want to extend your harness, then just make sure to splice the wires one at a time when you're adding in the extra run, so you can keep track of which is which.

My engine, harness, and ECM came out of a boat, and I did not have any factory controls. I had to do a lot of figuring and modifying to fit my existing harness. In fact, I'm using the tachometer from an AR-230 jet boat. It uses an 8-pin plug, which I was unable to find, but was able to make my own pin connectors and then sealed it with marine grade silicone. Works just as good as a plug.

As for the reverse bucket, it should do OK. I'm using an XL1200 pump in my boat, which has a very small reverse bucket, compared to the newer Yamaha 4 strokes. Still, it's ample enough for my application. If you're going to use a reverse bucket off a Yamaha FXHO, that should be more than enough. I say that because we own a VX110 Yamaha, and if I let off the throttle at 20 MPH, hit the reverse bucket, and then hit the throttle, the bow of the jet ski will do an instant nose-dive, and it will almost put me over the handlebars. It's the same reverse setup on the FXHO as the VX110 and FX140.
Regarding hull size I'm working on the same assumption. Harbercraft of Canada used to build an 18ft shallow V with the same Engine, 72" beam weighing 1800lbs.
I calculate the current setup to weigh +_ 340 kg (750lbs) which is not much more than the original Ski, 72" beam with am estimated 18' wetted area. My target weight completed is 1500 lbs.
The donor Ski was complete, and when run on a hose everything worked except the kill switch, as a result I did not run the ski on water. With the Ski parted out I eventually found a broken earth wire in the middle of a harness which I trust was the cause of the kill switch problem, but still a very strange break, and the first time I have seen something like it.
I hope you are right about the reverse bucket, after all the work done to date, it is the one area I expect to revisit.
As mentioned I read your build thread cover to cover, but still managed to miss the bit about the XL1200 pump, blissfully unaware I spent many, many hrs fabricating the tunnel and pump adapter plate, and still don't know if it will work, the XL1200'pump must be the preferred option.
Thanks for your input.
 

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CedarRiverScooter said:
I am so jealous . . . Looks really nice!
Thanks CedarRiverScooter, nothing to be jealous of yet, still just a pile of aluminium and a bunch of ideas aiming to emulate what you guys have already done.
 
Ranchero50 said:
I think it should scoot along pretty well. Narrow hull will act like a destroyer and should cut pretty well. I'm wondering if it wouldn't like a couple guide strakes further forward though. Testing should show if it turns lazily.

Stomp grate to avoid swimming with the croc's? Good idea. =D>
Thanks Ranchero
The hull is a full 72" wide at the beam, but I do hope the displacement will allow the boat to carry weight and get on the step at a reasonable speed,
I am with you on placing a strake further forward, I was thinking of removing all the strikes at the back of the boat and adding one on the keel at about 2/3 length. The thinking is I need a pivot point for slow handeling in narrow channels antd hopefully it will provide stability at speed.
Strange you mention crocodiles, the first time I piloted a Outback hull was in support of Brad Besterlink and his wife Andy filming their natural history documentary "Diving with crocodiles" learned two things that day, I liked the outback hull, and my friends are mad,
Thanks for all you input on the forum it certainly is of massive assistance to guys like me trying to get ideas in remote locations
 

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Correction I learned three things, the third was after reviewing their film footage of the day, and as Ranchero rightly points out, with Croc's and Hippo's a stomp grate is a must. I might have gone overboard on this design, but the motivation was high.
 
Okavango, since you have already fabricated your intake duct, the rest of the pump assembly should work with it, as long as you have the bolt pattern and length set for the driveshaft and pump that comes out of the ski. Quite a few others have done it like this.

I used the XL1200 pump since it was a prefabbed, bolt-in design. In hindsight, I could have probably fabricated my own intake duct (and made it from thicker material than what the factory uses)...but at that time, this was my first go-around with building a jet boat, and there were no online sources of info like this forum to help me figure it out.

As for the reverse bucket, you shouldn't have any issues with it. Just remember when you set it up, to position the cable thru-hull at the transom where the cable travel is set so that when it fully extends, the reverse bucket is all the way down, and when you retract it, that the bucket is clear of the steering nozzle outlet. You may have to create a stand-off, to bring the cable a little farther out, or farther in, than your transom, to make it line up correctly. That's what I had to do, but it works fine.
 
Hi PSG
Sorry about the tardy response, but I am in South Africa at present.
Thanks for all the input and I remain hopeful of success, I return next week and will endeavour to get the boat in the water for trials.
Kind Regards
 
Newb here. I happened to see PSG-1 brought up the topic of the different reverse buckets. I have the xlt 1200 power train in my 1872 and the reverse is not good. Does anyone know if the newer dual outlet bucket will fit on my jet? Thanks for your help in advance. - Dustin
 
Kustom kid, welcome to the board.

As for your question about interchangeability of reverse buckets......no go. Already looked into doing that with mine. The newer dual-outlet type reverse buckets are designed to attach to a bracket on the PWC or boat. The XL1200 style attaches to the steering nozzle. You would have to design a whole new set of brackets to mount it on. Also, the ball joint fitting for the control cable is in a different place on the plastic reverse gates than it is on the XL1200.

Not saying it can't be done, but you'll have to do some modifying, for sure. One day, I might decide to upgrade to that type of reverse bucket, as my reverse is only so-so, it's enough power to back off the trailer, etc....but nothing like the power you get from the newer dual outlet reverse gates.
 
Thanks for the welcome, and the reply. That is a bummer the bucket does not fit. I found one for $43 new. I might get it and see if I can't make some brackets. I have def wasted more than $43 on things that don't work, so it won't be a huge loss...lol
 
Not very pretty but all temporary controls work and I am ready for river tests tomorrow, wish me luck
 

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I love the handle bars, thought about doing something similar until I found the go cart wheel and used it instead.
 
Ranchero50 said:
I love the handle bars, thought about doing something similar until I found the go cart wheel and used it instead.
Hi Ranchero, great thing about parting out a Ski is you get all the bits to use in your boat, I will certainly use the instruments, but I think jet steering is the way to go.
 

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Over the moon with today's testing. With the exception of reverse, only minor adjustments where needed to set up trim. PSG you where spot on, what an engine. 44 MPH GPS one up, 42 MPH 2 adults 2 teenagers.
Cruises at 36 MPH 7500RPM 3100ft ASL.
Some cavitation if you dump the throttle one up, but this will improve as I complete the build and add weight. Four up you can launch and get on the plane in a boat length.
This was the best fun I have had on the water in a long time, could not believe how responsive this 20ft boat is.
Will try all up weight runs tomorrow, reverse tends to pump into the jet cavity and is almost non existent so some thought and work needed there. Any suggestions on how to resolve this issue?
Might have to change the nozzle and reverse gate to the jet boat set up, but would hate to loose trim as you can feel when adjusting the trim how the hull releases and speed picks up.
All in all a very satisfying day, posted some video of a fantastic day on the water, mid winter in Botswana!
 

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