What to use to cut clean, lightening holes in crossribs.

[dannyUAL767]

When I start building my next boat (which will be soon), I want to cut lightening holes out of the ribs. I'd like them to be as clean as possible with minimum splintering, etc. What are you guys using? Just a standard hole saw? Someone on another thread mentioned Forstner (sp?) bits :confused: .

[riche]

Forstner bits would be the best. either one will work, just find a scrap piece of 2x4 and clamp it down good before you strart.

[Hydro Junkie]

All I use is a holesaw and a Dremel Tool. One word of caution on the lightening holes. Don't make them too large, or the frame will become too weak. Depending on the boat you are building, a couple of smaller holes can work better in weight reduction than a large one. What boat are you going to build?

[dannyUAL767]

Chilly from this forum has sent me a set of autocad plans that my buddy will be printing out for me. It is a large mono that resembles the smaller Wild Thing.

I'll also be starting my Dumas Miller American 1/8 scale. I've ordered a bunch of Okoume plywood and it should be here by the end of the week. I got a Craftsman jigsaw for Christmas so I'll be cutting out some new parts for this boat out of thinner, lighter wood like you recommended!

[rc10gtisthebest]

Make sure you use a finer blade when sawing the ply. Also, try and go with the grain if possible (will help reduce splittering).

-Todd

[dannyUAL767]

Todd, I'll definitely use a fine tooth blade. I had the wood company cut down my 8'X4' sheets of Okoume ply to 4'X2' with the grain going longways. It was much cheaper to ship the smaller wood than to keep it large. Right now, I have no plans of building a really large boat and something 48" long will be big enough, even for gas.

[Hydro Junkie]

A 48" gasser, sounds like fun. I would caution you though, that depends on the type of hull. For a vee, not a problem. For a hydro, I would look bigger, like high 50's to low 60's for length. As you may know, a hydro doesn't have a lot of freeboard or weight carrying ability, so bigger may be better in that case.

[dannyUAL767]

posted by Hydro,
A 48" gasser, sounds like fun. I would caution you though, that depends on the type of hull. For a vee, not a problem.

Now I actually thought that a 48" gas mono may be a little small because it looks like many gas monos are longer than that.
My wood is in 4'X2' pieces so that is why I'm looking at 48" long boats. I could always just glue pieces together if I really want to build a bigger boat. I think the actual plans are for a boat that is 57" long.

As you may know, a hydro doesn't have a lot of freeboard or weight carrying ability, so bigger may be better in that case.

I thought that guys are running 1/8 scale size hydros with gas engines :confused: . I thought that I'd even seen 3 point hydros in person that were Zenoah powered and less than 48" long but maybe I'm wrong. I was thinking of going ahead and tracing out the parts to my Miller American and building another lighter hull and putting a Zenoah 260 in it.

[suck my wake]

most 1/8 scale hydros have like a .67 in them for competition purposes. Maybe your thinking of the pro boat miss bud 1\8 scale.That has a zenoah in it

[dannyUAL767]

Well, I just thought that guys were putting gas engines in the 1/8 scale boats not so much for competition but just for easy, reliable fun. I went on the Aeromarine website and saw that their 1/8 scale boats are for 11cc engines and that they have a large 50" sport hydro for gas so it looks like I was wrong :( .

Still.......I figured that I could run the gas engine but according to Hydro Junkie, "a hydro doesn't have a lot of freeboard or weight carrying ability." But then again, the 1/8 Miss Bud has a gas engine. I think that I could build one of my 1/8 scale boats to accept the gas engine.

[BoatDoc]

a lot of 1/8 scale hydro's use gas engines. i think that HJ was just trying to make a point. gas engines weigh more than nitro engines...and hydro's need to be light as possible. personally, if i was going to build a 1/8 scale...i would drop a .67 in it instead of gas. however, gas is pretty popular for a 1/8 hydro. if you want to build a 1/8 gas hydro, you will need to pay extra attention to the weight of all your components to make sure that it is light as possible.

[dannyUAL767]

Thanks for the clarification, BoatDoc. I didn't think that I was crazy :D ! I've got a big shipment of Okoume plywood on the way to me. HJ has given me a lot of advice about losing weight with heavy Dumas kits. I think that I can lose a lot of fat with this new wood.

I'm currently working on a father/daughter boat, the Dumas Lil Rascal. I've already made the mistake of using Dumas' too thick, too heavy wood for the sponsons :mad: . By the time I really took a good look at the wood and thought about its unnecessary thickness, I was 90% complete :( . I've been paying good attention to not slop on too much epoxy. When I sealed the wood, I took good forum advice and used a paper towel to wipe away the excess. My bare hull is already 1lb and its only sealed on the inside :eek: . This complete, painted hull probably shouldn't weigh that much. BTW I did cut two 1" holes out of each of the two sponson brackets. They are really thick and they lost a noticeable amount of weight.

Wow, I turned this post into a novel! Anyway, I'm thinking that I can be smarter about the wood, cut good lightening holes and use smart building techniques to build a lighter boat that will work with gas power :D .

[bufferoo]

The simplest and easiest way of drilling clean holes, regardless of what type if bit you use is to clamp the piece you want to cut the hole in between two other pieces of scrap wood. The bit will act like the whole thing is one piece of wood and any tearout will happen on the scrap pieces leaving your piece clean as a whistle.

Bufferoo

[Hydro Junkie]

You are partially right, Boatdoc. My point is this; the average size of a .67 is about 1/3rd the size of a Zen. The Zen needs a 7 inch wide engine bay(unless the exhaust and carb are exposed and above deck level) where almost all 1/8th scale boats are designed with a 4 to 5 inch engine bay. Without major modifications, the Zen won't fit between the engine bay bulkheads. If the boat you are building has a cowled over engine, the 6+ inch tall Zen will be sticking through the top of the cowling(except in some of the turbine boats). Since someone mentioned the Pro Boat Bud, Horizon got away with it by sacrificing strength for light weight, though pics I've seen of it on the water still have it almost swamping at the rear, while a nitro boat the same size has two to three times the freeboard. They also had to distort the cowling to get the exhaust and carb under the cowl. I still recommend going bigger if you want scale.

[dannyUAL767]

I've started a thread about 1/8 scale gas boats on Jim's R/C Boat Dock. It looks like the general feeling is the 1/8 scale boats are too small. It looks like they tend to blow over pretty easily. I've had that happen once to my Aeromarine Avenger with Zenoah 230. Not fun!

It looks like I could trace my current parts out and try to have them enlarged (10-20%?) at Kinkos or some place like that. I was even given the idea of just buying a set of plans for a large gas boat called the Whiplash by Brian Blazer. I'm trying to find info on it/him.

[Hydro Junkie]

If you plan on going bigger, go 33%. The larger hull will be in the 59" range, but will be able to handle the torque of the Zen.

[dannyUAL767]

I could certainly have my traced lines scaled up that big but I just don't want the hassles of trying to transport a boat that big. My AM Avenger is about 45" long and its a pain to transport. I do think that a gas scale boat is going to need to be about 50" to be stable.

[dannyUAL767]

About the clean lightening holes, I'm going to sandwich my pieces of wood between scrap to keep the cuts clean. I'm going to purchase an inexpensive, made in USA hole saw set from my local Eglin AFB Base Exchange: $7.95 for the mandrel and 4 or 5 saws. Lowes was way more expensive and made in China.