intro - noob with a big empty hull and a lot of ideas

[ITOYMWYA]

Hello all!
I am the longtime owner of a 46" Prather deep vee that I now want to create into an electric monster, rather than the original design of a noisy, messy line trimmer engine. Im going for a very robust and powerful setup, rather than race. I will be running it on open water like lake Ontario.

Here are my ideas on hardware and where the project is headed:
(i dont mind doing things differently, unless there is a damn good reason not too)
5692 motor with 75mm cooling jacket
8s with 2 packs
1/4 flexdrive strut with skeg, 3/8" from cl to bottom of boat. (have an X-470 3 blade to start)
dual rudders
keel turn fin (already installed)

Im a mechanical designer, I use CAD, and have lots of experience with RC, having built subs (3), kit boats and a soling sailboat.
For the curious; ITOYMWYA = Im The One Your Mother Warned You About

Know anyone that has done a simillar project, and the hardware they used?

Regards,
Brent

[Fluid]

Use of the Prather hulls is not common, but similar sized hulls are often converted. The most important thing is to fabricate a hatch which seals 100%. Period. You will have terrible failures running in rough water with a leaky boat. Running 8S makes sense, as does the motor size. But the Kv will depend on your speed, prop and run time expectations. The 70mm props are gas props, using a stepped down 1/4" flex cable opens up prop choice and motor choice. Lose the twin rudders, not needed and extra drag. Use SpeedMaster gas rudder and strut. Install a "wet well" so the strut has adjustability. Allows a much wider range of props.Keel turn fins are not used on modern monos. That gives you a start, a search will show you similar builds..

[DCMW]

I have a 5692 with jacket if interested let me know..

[ray schrauwen]

Hey Brent, made it on here I see.

Guys like fluid know big boat setups better than I do but, I can help you get some of the goodies to go inside from places like OSE store and beyond.

Just about to crash for the night.

Later....

[ray schrauwen]

Let's try and load some pics. Brent has since taken the hardware off the transom and weighed the hull empty at 4lbs ish.20151013_224448[1].jpg

20151013_224431[2].jpg

20151013_224506[2].jpg

[ITOYMWYA]

Thanks for posting the pics Ray, it helps a lot. I will continue to take lots, so I can document a build thread here.
Bare hull weight is 4lbs 9oz which seems quite light considering it is a 46" hull. Considering it will be used in rough conditions, I will be bracing and beefing up the hull more to be sure.
Thanks for the sage advice, Fluid. Now to look up what a 'wet well' is.
Good point about the hatch. Seems obvious, but sometimes idiots like me are ingenious.
And the stepped drive line: I assume the brass bit on the outboard end of the flex is over-bored to accept the 1/4" flex cable, but still has the 3/16" bore to drive the skeg shaft. Is that correct?

[ray schrauwen]

Please go here to see my df33 mono. It shows hoiw I built everything. Wet well, etc...

Yours is just bigger.

You might need to sign up to see pics...

http://www.rcgroups.com/forums/showthread.php?t=866149

[ray schrauwen]

Some pics of wet well and business end...

a1875366-46-E2 mono BUild 009.jpg

a1875367-144-E2 mono BUild 004.jpg

[klbo]

Here's a quick video Of a central marine fountain 58 doing a flyby I just finished with a single Castle creation 2028
motor

[ITOYMWYA]

I saw that video when I was searching through the big mono builds, that is incredible!! Nice work klbo. Love that sound, I would like to know more.
Is there a build thread, or gallery pictures of the running hardware?
Its the hardware choices that I am stumbling on. So many options, lots of opinions, and not a lot direct experience yet on my part.

[ITOYMWYA]

Now i have figured out what a wet well is. Flooded opening through the hull that allows the stuffing tube to be adjusted way more. As the center of my drive line is below the hull bottom surface, a wet well wont do me much good.
Going to keep the prop mostly buried, and retain the dual rudders for now. I can always re-do it later, that doesn't bother me. I don't like big rooster tails. Twin outdrives could look nice too, but I dont know much about them, or if they can handle the RPMs and speed.

[ray schrauwen]

You will have little success with the depth of your drive strut.

Very few people build boats that way anymore. If it was 1970, I'd say go for it!

If you don't support the drive cable in a stuffing tube, Teflon liner or not, there will be problems.

[ITOYMWYA]

Completely agree with supporting the total length of the flex cable in a stuffing tube. Don't want that whipping around at 20k RPM.

Guess I need to see some boats and the hardware they sport, to understand better. What are the advantages of a surface drive? - Don't say speed, because its not a primary priority to me. I'm a technical guy, i wont do something just because the whole flock does it, I need to understand the WHY of it, to do it.

I guess I need to better explain my expectations for how the boat will be used and perform:
-I want to used the boat on flat calm lakes, as well as on open water with waves up to 24". (this will require some decent hull bracing, and strong points of attachment for the equipment)
-Top speed 50-55MPH max.
-Decent run time (10-15minutes?) -second set of batteries to swap after motor has cooled

So what makes a surface drive on a Deep Vee so popular? -It makes total sense on a rigger or Hydro as the third point of stable contact to the water.

[ray schrauwen]

I just don't know anything else but surface drive. I understand jet drive and outboards but submerged drive is only for scale as far as I know. I've had no experiences to share with you if you decide on submerged drive. No idea where to point you???

[ITOYMWYA]

Surface piercing props can spin as fast as they do because theoretically they are only in the water half the time. On full sized offshore boats, the throttleman cuts back on the power when the props are fully airborne. If I knew the boat wont be launching itself off of waves at high power settings, then im fully in the surface piercing camp, but it will be bouncing a lot i figure. Going lower than usual, (blades still catching some air) makes sense to me, as the prop will be in the water more than if it were higher.