Mini-V w/decoy duck jet drive build

[damfurst]

The project is to use the jet drive out of the duck decoy and install it in a mini-v hull. I know some of you are wondering why a mini-v. It's simple I still have a couple of these hulls that I bought a couple of years ago and I wanted another mini-v jet drive boat since my other one is in Davey Jones locker since last year. So I'll be making some improvements to the hull and factory flotation along the way. For this post we'll tear it down so we can build it back up.

I weighed the new mini-v on scale and it came in at 286.4 grams w/o battery. So all the inards come out along with the shelf that's glued in with the servo mount and spots to hold the receiver/esc and battery. Everything went well until I hulked out on the last piece and took part of the hull with it. Not good, but I plan to fiberglass the inside of the hull to reinforce it (mini-v hulls aren't very stout to begin with) Probably have fill and sand as well. So a little extra work, but it'll come out in the end.

[damfurst]

Made a little progress last nite on my project. I did a before and after pic of the flotation foam in the bow of the boat. What they come with isn't much and it will barely keep the boat afloat (experience). When I had my mini-v with the 22mm jet drive it I made the mistake of not adding more foam to it. Thus one day when it started to sink it went all the way and I've not seen it since. Don't what that to happen again so I mixed up some of my expanding foam (about 4 drams worth don't know what a dram is but that's the marks on the cup that I used to measure) and poured it in the bow and 10 minutes later had the results shown in the pic. This stuff expands over 10 times the original mix. That part done I went on to the fiberglassing. First I glued the part of the hull back in the hole I created and then I scuffed the inside of the hull with some coarse sandpaper. I used 2 strips of heavy cloth fiberglass tape, laid them into position in the hull, and then mixed and poured the epoxy onto the fiberglass. I used a small roller picked up at Ace and worked the epoxy around the hull covering all the fiberglass and working it into the corners of the hull. This morning everything is dry and the hull is stiff as a board. This added about 24 grams to the hull so now I'm sitting at 114 grams.

[LarrysDrifter]

Drams,thats kinda funny,never heard of that.I like what your doing,but if it were mine-and I know its not,but I would have fiberglassed it all the way forward before foaming.That way the entire length of the hull is stiffened up by F.G.Just my opinion-doesnt mean what your doing is wrong.Ill be watching this build.

[damfurst]

Made a little progress yesterday. Took x-acto knife and cut out hole in bottom of hull. Next- hole in the transom so that I can get the drive mounted.

Larry as far as drams go I don't know what that means either other than 4drams is opposite of 1/2 fl. oz on the cup.

[Jesse J]

Sweet! now I know what to do with my spare mini V... I will be curious to see how it turns out, but knowing you and your knack with jet drives - I bet it will be awesome.

[antslake]

This is cool. I have 2 mini V's waiting for mods. I figure to use them up a bit until they die. I've been wanting to do a jet-drive too. Love it.

[damfurst]

Thanks Jesse and antslake. Appreciate the comments.

Yesterday I worked on getting the drive mounted into the boat. All in all it went well. Only had sight issues with having the enlarge the hole through the transom because it was about a 1/8" too high. Also getting the grate to mount flat took some extra cutting the hull that wasn't anticipated. The hull is too stiff the flatten so had to lengthen cut part of the hull that was taken out both in the front and back of the drive. This left a gap in the front between the hull and drive body of about 3/16". I'll have to fill this with shoe goo when I glue the drive into the hull for permament. There is a binding issue for the rear of the drive because things don't exactly sit square. Will have to work more on that. Anyway, The way the drive sits in the hull now looks good to me. The lines of the hull definitly look better the whale or guppy shape of my first mini-v or even of drangonfires. Hope it handles well also. However, there is room to put a delta in front of the drive if needed. Will see how it runs first though. Here's some pics. Weight with drive now is just under 150g.

[antslake]

Looks nice! Looks like it would have power!
One thing I noticed, just like on my real jetski, the height of the intake grate is important, you might want to make a flat spot in front of the intake grate to smooth the water out entering in. If not you may get more cavitation than you want, because of the V in the hull.
can you purchase the drive separately?

[damfurst]

Looks nice! Looks like it would have power!
One thing I noticed, just like on my real jetski, the height of the intake grate is important, you might want to make a flat spot in front of the intake grate to smooth the water out entering in. If not you may get more cavitation than you want, because of the V in the hull.
can you purchase the drive separately?

Yes you're right. I purposely left the hull like it is to test this profile first and then if necessary I'll do the delta in front of the intake.

You can buy the drive and impeller seperatly from Horizon Hobbies. The one thing they don't list however is the connector between the motor and the impeller shaft. It appears also that the Mini-V brushed motor is the one they use also with this duck, so I'll be trying that motor first before I go to brushless. I got a bunch of Mini-V, C stuff so might as well use it for something.

[GeoVW72]

They finally added the coupler to the catalog
I've had a hard time finding one that works, what are you using?

I have a duck and they are using the mini-v motor with a simple coil cooler, there's a pick up on the nozzle.

Good work, I'm definitely curious to see how it runs

[damfurst]

They finally added the coupler to the catalog
I've had a hard time finding one that works, what are you using?:

I found a 2.4mmX3.18mm coupler here at R2 hobbies. I does fit but I'm not real sure on the alignment (might wobble a little) which isn't good. May have to wait until they come in at Horizon Hobbies.

Been working on painting here lately and patching the hole in the hull. I'm no expert at either but do what I can. Here's what I have so far.

[antslake]

Aluminum foil makes good shim material.

[GeoVW72]

I'm having the same wobble issue with a brushless decoy build
went a different route shimming down a large coupler with brass tubing

Knowing Horizon and their boat parts it will take some time, 2/20

[damfurst]

I'm having the same wobble issue with a brushless decoy build
went a different route shimming down a large coupler with brass tubing

Knowing Horizon and their boat parts it will take some time, 2/20

What brushless motor are you running in your duck? I plan on running either a 3000kv Mystery or a 3100kv esky. If you had a pic of the insides would be great to see also.

[wparsons]

Any chance you have the link to the jet drive on horizon handy? How big is the drive compared to the graupner mini jet drive? I've been trying to find one of those, but it seems that everyone is out of stock.