HELP! Building First Hydro dont have a clue

[la_zcar]

Im building a Dumas Miss Unlimited (36" shovel nose hydro) but i have one problem I dont have a clue how to set up a hydroplane. If any body has any tips or knows where I can find any info on motor and prop selection that would be awsome.

[ROOSTERTAIL]

Im building a Dumas Miss Unlimited (36" shovel nose hydro) but i have one problem I dont have a clue how to set up a hydroplane. If any body has any tips or knows where I can find any info on motor and prop selection that would be awsome.

Are you looking for a brushed or brushless set up ? That boat does quite well on a Psport set up. 8 XL 12 NIMH cells or correct lipo. Most any of the 100amp or above escs. For a prop start with an X438 and go from there. I would not go larger then a 442 prop without knowing your amp draw if you want to go bigger be sure of your amps at X442 first. So you may need a data logger to use larger props then a X or M 442. Also a wire drive will help lower your amp draw a bit.

[la_zcar]

First off thanks for the help. Thats what I was figuring Ive got a 9xl I was gonna try with a Hydra 120 on 12 cells. my main question is props i heard you should run a lifting prop what is the purpose and which are lifting props

[ROOSTERTAIL]

You have the right set up. The X or M props are not high lift props but do work very well on this set up and most hyddros, . My 34 inch wood hydro runs 60 + mph at 5lbs totoal weight on the water running 12 IB 4200;s, An M prop is simply a detounged X series. I highly recommend an adjustable strut and wire drive!!!

[la_zcar]

awsome this is just being built as a play boat im gonna make it look as nice as posible so top speed doesnt have to be much over 30 what prop would you recomend for good run time

[ROOSTERTAIL]

awsome this is just being built as a play boat im gonna make it look as nice as posible so top speed doesnt have to be much over 30 what prop would you recomend for good run time

The 438 or 440 will get you the best run time anf very good speeds. Try to build the hull as light as possible. Dumas hulls are a bit on the heavy side. Think your build through and try to save as much weight as possible by drilling and removing some of the center wood of the bulk heads and such where ever possible with out comprimising srtuctural integrity.

[la_zcar]

cool ive got a 440 lying around some where ill have to give that a try. hey didnt you build a cat whith a sv27 setup awhile back

[ROOSTERTAIL]

That was a past project!! For the cost worked well!! I had it posted and the entire build on another sight!

[la_zcar]

That was a past project!! For the cost worked well!! I had it posted and the entire build on another sight!

k i thought that was you i was thinking about doing the same with a28" cat i have. what was the length of your cat

[Fluid]

I'm sorry, but I have to strongly disagree with the recommendations above. The Dumas 36"hull is heavy and has a poor sponson design for limited FE power. It will not work 'well' on 12-cell power. A previous club member built one and never did get it to perform satisfactorally. This is not a mono that will run 'okay' on limited power - it is a hydro and if it does not plane it will suck amps big time and destroy your equipment.

If you insist on trying it, you will want at least 18 cells/6S to make it plane decently with good run time and without burning up your equipment. You can use your 9XL on a gear drive or a lower Kv motor direct. That hull size will want at least a 42mm prop to get decent performance. A 38mm prop has a very small thrust cone and the boat will have trouble accelerating out of turns, assuming it even gets on plane in the first place.

One club member runs a custom-built shovel (a true scale model of a real Unlimited hydro his father raced) about that size, but much lighter and with excellent sponson design - see photo. He runs 18 cells and an XL motor, I do not remember which one but around a 14XL. That boats runs great with scale-like performance and is a great sport boat. But it weighs at least a pound less than the Dumas and has plenty of lift from the sponsons to get it on plane...


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[la_zcar]

would any body know how to contact the guy that owns that boat?

[Fluid]

I'll find out what I can.



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[ROOSTERTAIL]

I'm sorry, but I have to strongly disagree with the recommendations above. The Dumas 36"hull is heavy and has a poor sponson design for limited FE power. It will not work 'well' on 12-cell power. A previous club member built one and never did get it to perform satisfactorally. This is not a mono that will run 'okay' on limited power - it is a hydro and if it does not plane it will suck amps big time and destroy your equipment.

If you insist on trying it, you will want at least 18 cells/6S to make it plane decently with good run time and without burning up your equipment. You can use your 9XL on a gear drive or a lower Kv motor direct. That hull size will want at least a 42mm prop to get decent performance. A 38mm prop has a very small thrust cone and the boat will have trouble accelerating out of turns, assuming it even gets on plane in the first place.

One club member runs a custom-built shovel (a true scale model of a real Unlimited hydro his father raced) about that size, but much lighter and with excellent sponson design - see photo. He runs 18 cells and an XL motor, I do not remember which one but around a 14XL. That boats runs great with scale-like performance and is a great sport boat. But it weighs at least a pound less than the Dumas and has plenty of lift from the sponsons to get it on plane...


.

I think you need to check out current 1/10 scale set ups.Were are you getting won't run on 12. Totally wrong I have built 2 of these and If you build them LIGHT they can be made to RUN just Fine !!!!

[Fluid]

Please don't get your panties in a bunch. I have over 30 years of FE experience and am fully aware of current 1/10th scale setups. Sure, a hull designed for this level of power built by an expert can do it. But a newer boater building his first heavy 36" Dumas hull (designed for .35 nitro power) will see nothing but trouble.

I've counciled far too may newer boaters having problems to recommend a 12-cell racing setup in this huge hull. I have learned not to project my own needs, desires and level of experience upon others. If you or I were standing next to him during the build and rigging then fine, 12 cells might work okay for him. But building by himself he will have disappointing failures. Remember he is not a racer, he is a sport boater. He will have longer run times and lower amp draws using 18 cells rather than 12 and he will enjoy the boat a lot more.

The OP is free to decide whatever setup he wants to use of course. I just prefer that he have a good chance at success rather than be almost doomed to a failure.

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[la_zcar]

Thanks guys yall have been a big help. Fluid that would be awsome if you could find a way to contact that guy for me if so just drop me a PM. You have a point about this being a heavy boat but Im gonna cut as much weight as possible in hopes of making it perform better. this thing is NEVER gonna race. Im actually building it for my father as a birthday present and it will probably sit on a shelf more than anything unless he comes with me to run it he wont drive it. like i said if it gets on plane and does 30mph I'll be very happy.