Hhhhhmmmmm, anybody seen a ducted fan hydro ?.....

[gsbuickman]

I just scored a sweet vintage boat from a good friend. This is an 80's built, glass' over wood recreation of the 1964' Miss Notre Damn shovelnose unlimited hydro.

She originally came gas powered with a .40 motor, turning a 1/4'' flex shaft in a 5/16 stuffing tube, spinnung a bigass Octura X680 berillium prop.
An electric conversion is as simple as epoxying in a motor mount, connecting the coupler, adding floatation & connecting the power. But since I need to finish the mold for the front of the cowl, & lay glass over it to make the new front cowl hatch piece, I had a second idea.

What if I pulled the rear cowl piece off, and made one long flat hatch plate to seal the hull up, then use a high thrust ducted fan motor or two for propoulsion. I could even pull the strut, stuffing tube & the prop to reduce drag. That way when its up on plane, only the sponson bottoms & the rudder are touching the water.

The hull is 36 1/2'' at the edge of the shovel, with an 18'' beam. The hull itself is 2.5'' thick at its thickest point, and the sponsons the boat planes on are 3'' wide with an 1 1/2'' rise onto plane. I thought about it before, & I know its been done. There were a handfull of ducted fan hydros online.

I was wondering if anyone has seen it done, and/or what your thoughts are ?. Thanks

[gsbuickman]

Think how flat & aerodynamic this hull would be with a flat hatch cover, v's a 2 piece cowl the tat originally use too cover the nitro motor & exhaust.

I seen a Budweiser hydro once, w/o a drive system & only a rudder out back. in the center of the front of the transom was a motor mount w/ an airplane motor mounted in it. It was pushing a 6'' prop. That boat would flat out haul arse...... Funny thing is I am pretty sure he ran it on 3s with a 30amp plane esc.....

[Peter A]

I've seen ducted fans used on a wiggy. A wiggy is a wing in ground effect machine. Google it, they are quite cool. The ruskies made a huge one called an Ekranoplan.

[Fluid]

Ducted fans do not work well on boats if speed is the goal. They have MUCH less thrust than a similar-powered air propeller, and they have poor efficiency particularly at low speeds - they work great above 60-80 mph. You might get the boat on plane with an EDF, but probably not.

An airplane magazine did a project with a ~36" hydro running a 7.5cc ducted fan some years ago and the speeds were very disappointing. I have seen similar hydros running air props and they run okay.


.

[gsbuickman]

Thanks guys. I am planning on visiting our local airplane guru Jerry Clark. Jerry is a cool ol' fart about 80. He builds all the planes for hobbytown & other customers. At any given time he has 500 planes on hand, in his garage & his hanger. He has everything from micro's to 1/2 scales that are 15' long with a 20' wingspan. You know how ol' farts with wisdom are, if it can be done, they'll know how to go about doing it ........


I would love to do a jet turbine like a couple guys here have, but i don't have $10k laying around for a motor. Thats what got me thinking about an EDF setup ....