Pursuit jet boat

[srislash]

Good day guys, I have moved to a new area of British Columbia and have been setting the property up so I haven?t posted in some time. But alas my hobby shack is working now so my first project is to convert the dog boat to a jet boat. Let?s start with George
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And my once beloved Bling Rocket

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So the new location has a beach nearby which has a great shallow area and a great space for George to chase the boat. But I need this boat to be a jet boat for safety reasons now. BTW, the boat is beat up from George rescues, he is so proud of himself when he rescues it.

[srislash]

So this is what I have so far as of yesterday:
Boat gutted and a TFL jet drive, layout of hole

My CG should remain close to where it was. Motor is yet to be determined.

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I?m not sure if I should widen the flat intake area or keep as much of the V as possible. I?ll take a few more speculative pics and report back.
Any input as to motor size and such is appreciated. My thought here is that the boat must be faster than George can run in 1.5ft of water and really prefer it not to just spin out when I turn.

[a53hoop]

where about in bc are you. i am in salmon arm and have no boats guys that i can find any were near,AL

[Panther6834]

I don't know anything about converting a V fire a jet drive...but, I do have a TFL Jet Boat. Looking at the bottom, there is 5mm of flat hull area on each side of the jet drive. I can't get calipers inside the hull to accurately measure spacing...but, to the best of my judgement, I'd estimate there's approx 2-3mm (closer to 3mm) of visible hull of each side of the drive. Not sure if this will help you...but, if it can, all the better.


~ More peace, love, and kindness would make the world a much better place

[srislash]

where about in bc are you. i am in salmon arm and have no boats guys that i can find any were near,AL

Hey Al, I moved to the hills just west of Oliver, Fairview area.
Shawn

[lilbigmacky]

I'm interested in this as well. I have always been a fan of jet boats and wanted to build an rc one. Im not sure about how removing the v will affect the ride but I know you dont want to restrict the intake because less water in means less water out which reduces thrust.

[srislash]

I don't know anything about converting a V fire a jet drive...but, I do have a TFL Jet Boat. Looking at the bottom, there is 5mm of flat hull area on each side of the jet drive. I can't get calipers inside the hull to accurately measure spacing...but, to the best of my judgement, I'd estimate there's approx 2-3mm (closer to 3mm) of visible hull of each side of the drive. Not sure if this will help you...but, if it can, all the better.


~ More peace, love, and kindness would make the world a much better place

Hey thanks for that, does be that hull have any spin out characteristics? I’ve had a couple of the old NQD jet boats(that’s where George started chasing boats). As soon as you juiced em up they started to be straight line boats. So I’ll try a couple hydrodynamic cues from them. I’m thinking a couple small strokes from jet pump intake to the transom.

[srislash]

I'm interested in this as well. I have always been a fan of jet boats and wanted to build an rc one. Im not sure about how removing the v will affect the ride but I know you dont want to restrict the intake because less water in means less water out which reduces thrust.

Yeah I think I’m going To taper the V forward till I get a desired ride attitude.
Surprisingly there is little on information on general hydrodynamics of jet boats and such. I have visited this subject a couple times over the years and do have a balsa/ply flat bottom with Graupner jet yet to see water.

[fweasel]

Jet boats typically have a flat ride pad. I would look at pictures of production models like the Thrasher and the TFL hull.

The only experience I have with running one is the Proboat riverjet I rebuilt for a project a few years ago. I would suggest under powering or under-volting it to begin with. Too much power on a jet boat makes for miserable control.

[srislash]

Jet boats typically have a flat ride pad. I would look at pictures of production models like the Thrasher and the TFL hull.

The only experience I have with running one is the Proboat riverjet I rebuilt for a project a few years ago. I would suggest under powering or under-volting it to begin with. Too much power on a jet boat makes for miserable control.

Hey there Ryan, yeah I’m going to stick with 20,000 rpm ish, maybe a 1600kv motor or something.

[Peter A]

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This is a jet boat I built earlier this year (during another lockdown). It was an old nitro flattie hull that I rebuilt to suit. Running the TFL jet unit with a SSS3674 1300 kv and OSE Raider esc on 4s. Runs pretty low current draw, I can get nearly 10 mins out of 6000 mah. I didn't want a super fast boat and am happy with the speed, it would be a fast scale speed, maybe 20-25mph. It does however spin out really easy so in due course I will put strakes on the front of the hull to try and keep the bow up in the turns. I have played with cg and turn fins but do not have it how I want it yet.

[srislash]

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This is a jet boat I built earlier this year (during another lockdown). It was an old nitro flattie hull that I rebuilt to suit. Running the TFL jet unit with a SSS3674 1300 kv and OSE Raider esc on 4s. Runs pretty low current draw, I can get nearly 10 mins out of 6000 mah. I didn't want a super fast boat and am happy with the speed, it would be a fast scale speed, maybe 20-25mph. It does however spin out really easy so in due course I will put strakes on the front of the hull to try and keep the bow up in the turns. I have played with cg and turn fins but do not have it how I want it yet.

Thanks for the pics and input Peter. Great job on that. I have an outrunner at 1100 kv here that is size appropriate, I’m not opposed to a purchase either, I’ll dig around.
How many amps are you thinking on ESC then?

[srislash]

So I have the hull cut forward now but the pics should demonstrate the hull attitude I mentioned

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[srislash]

I have the pump outlet all hogged out to fit, just need to drill four mounting holes and then it will be fill in the holes time

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[lilbigmacky]

I might build a flat bottom zippkits crackerbox in the future and put a big ol jet pump in there to see how it works. Id like to see how your jet projects turn out.

[Panther6834]

I've had this interesting/strange/crazy idea for the past year: a twinh jet powered cat. While it's still a few years (at least) from me even starting work on it, the biggest problem...and, the primary reason for an "extended delay"...has been finding a hull. The reason (which should be obvious) is because I haven't come across any cat hull as with sponsons that area completely flat (to watch other) in the rear, on which the sponsons are also wide enough for jet drives.


~ More peace, love, and kindness would make the world a much better place

[srislash]

I've had this interesting/strange/crazy idea for the past year: a twinh jet powered cat. While it's still a few years (at least) from me even starting work on it, the biggest problem...and, the primary reason for an "extended delay"...has been finding a hull. The reason (which should be obvious) is because I haven't come across any cat hull as with sponsons that area completely flat (to watch other) in the rear, on which the sponsons are also wide enough for jet drives.


~ More peace, love, and kindness would make the world a much better place

I am not sure the steps would be an issue. Odds are the rearmost one would be where the intake would be. The biggest deal with jet pumps is getting the speed. By nature they are pressure/thrust specific. I’ve been watching drag boats fight this for years.

BUT I LOVE THE IDEA!!! Maybe a river boat kinda thing

BTW, is the drive unit epoxied or siliconed into the hull floor from TFL?

[Panther6834]

BTW, is the drive unit epoxied or siliconed into the hull floor from TFL?

Epoxy


~ More peace, love, and kindness would make the world a much better place

[Peter A]

Thanks for the pics and input Peter. Great job on that. I have an outrunner at 1100 kv here that is size appropriate, I’m not opposed to a purchase either, I’ll dig around.
How many amps are you thinking on ESC then?

The Raider doesn't even get warm, nor does the motor. I think it would be ok on 90A. I am having some issues with water forced through the inside ring into the boat I just have to spend some time to reseal that area.
Also FYI, OSE has some M2 x 6 mm s/s cap screws to replace the rustable black ones that hold the nozzle on.

[srislash]

The Raider doesn't even get warm, nor does the motor. I think it would be ok on 90A. I am having some issues with water forced through the inside ring into the boat I just have to spend some time to reseal that area.
Also FYI, OSE has some M2 x 6 mm s/s cap screws to replace the rustable black ones that hold the nozzle on.

Thanks for the heads up on the screws Peter. In fitting the drive I have noticed that the drive through the collars will not be watertight all on its own. I?ll be tossing silicone around to mount the drive into the hull I think. Good enough for battery trays on a 100mph boat then I?m sure it?ll hold the drive in. And then if the transplant is a fail?

[srislash]

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Fill in pieces are done and old holes epoxied

[srislash]

Next was a layer of cloth tape over each fill in piece, some spare CF weave and one piece CF weave over it all. Placed and secured the pump unit in the hole using plastic shopping bag as a barrier, this ensures a nice fit for the drive later on final.

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The hull bottom is coming along, just trying to smooth it to aid in flow into the pump. I will use Featheright to fill/smooth the rest including the bad concave on the one side that was filled with glazing putty and failing.

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And you can see the rearward guides which I?m hoping will help with spin outs

[srislash]

Well as an update, Steve got the 4blade impellers in so I ordered one as well as a 3674 Leopard in 1400 kv. I still have to build out that hook but it’s gone cold and snowy here in the Okanagan, not to mention Xmas ��

[srislash]

Yayyy!!! My OSE order came in today as well as my 100ah Lithium batteries so hopefully I can get stabilized heat in the hobby shack

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[srislash]

Well I have been back at it. I got the pump unit installed permanent. Upon recommendation from Peter I was liberal with some silicone at the rings that bolt Thru the hull. Now I?m waiting on a CYS servo from evil bay. I didn?t really have a mini servo adequate for this setup so it wasn?t worth reworking a servo mount.

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Until the servo I am distracted by a 30? AC Lightning Cat that needs to get a start