How do I make compound curves on vintage hydro

[SteveDeligan]

Hi everyone,

This is my first post here. Just started collecting the bits for my first 1/8 scale hydro... the 1957 Miss Wahoo, and I have some questions.

First, I am an active RC sailor and have scratch-built a number of 45" RC sailboats (Star 45's, etc...) and have even written 100 page construction manual for how to build one. So I've got some building chops. I just don't have any power boat chops at all! I will of course have to learn how to set up the motor, esc, etc... so I'll have many more questions.

My first one though is this: I'm making the Miss Wahoo and it has a great looking mahogany deck that is obviously sheeted, not planked. I've also seen several scale hydros that have nice looking wooden decks. So my question is how do you get a nice compound curve on the deck with sheets of wood? Thoughts?

Thanks,

Steve

 

[dave weagel]

Hi everyone,

This is my first post here. Just started collecting the bits for my first 1/8 scale hydro... the 1957 Miss Wahoo, and I have some questions.

First, I am an active RC sailor and have scratch-built a number of 45" RC sailboats (Star 45's, etc...) and have even written 100 page construction manual for how to build one. So I've got some building chops. I just don't have any power boat chops at all! I will of course have to learn how to set up the motor, esc, etc... so I'll have many more questions.

My first one though is this: I'm making the Miss Wahoo and it has a great looking mahogany deck that is obviously sheeted, not planked. I've also seen several scale hydros that have nice looking wooden decks. So my question is how do you get a nice compound curve on the deck with sheets of wood? Thoughts?

Thanks,

Steve

steve,

the Wahoo is a beauty for sure. i think Leonard Feeback built a near perfect gas engine powered replica.

are you using the ML 1/8 scale framing kit ? if so, ask Mike L for much better advice than i can provide.

conventional round nose deck compound curves are a challenge. that's why many builders choose the dropped sponson "4 or 5 piece deck" hulls.

i'd suggest 3 deck pieces for the Wahoo but 2 pieces will have fewer seams.

one method is wetting the 1/16 ply deck sheeting pieces with paper towels soaked with warm water mixed with ammonia then taping to hull framing for shape. then "gluing" with 30 min epoxy. be sure to seal underside with thin coat of epoxy before gluing to frames.

i've used clamps, weights, tape, staples and screws to hold the 1/16th in place on severely compound curved decks. adding gluing sticks to the sides of the typically thin frame edges provides more gluing surfaces. Zippkits uses 1/8 ply for all framing parts which provides a rigid structure with more gluing surface areas. these are gas engine powered boats so added weight not as critical.

see the Zippkits.com web site round nose kit build instructions for much more information.

also see ken olson's gas scale round nose build thread on JRCBD.COM

another option is 1/32 birch ply and mahogany veneer top decks. but must be careful about sags between the framing members. add sticks over the larger open areas, 1/32 easier to shape over the compound curves than 1/16.

1/64 mahogany veneer provides a blemish free clear deck. tedious but easier than trying to get same with the birch ply decking and stain, imo. thin veneer will provide the Wahoo's mahogany ply sheeted deck appearance.

see "plane crazy's" blazer lauterbach with veneer decks build thread on JRCBD.COM

probably a dozen other ways to do this much better.

good luck

 

[Ray Sametz]

http://jrcbd.com/forum/showthread.php?2043-Lauterbach-Build

 

[Mike Cathey]

some guys have used the 1 mm Birch ply in sections and then covered it with Mahogany doorskin.

 

[Hydro Junkie]

Nonadhesive packing wrap

 

[SteveDeligan]

Thanks guys!

Mike: In two separate steps, or as one lamination? I would imagine two separate steps. I thought that if I used 1/16" mahogany that I might be able to skip the plywood step. But my real question is "how do you get the compound curve?" Will the wood conform to curving in two directions.. fore and aft and crosswise?

Hydro Junkie: Are you saying that using the packing wrap will make the pieces conform to both curves? It will hold it down well enough to do the compound curves?

Thanks!

Steve

 

[Hydro Junkie]

If wrapped tight enough, yes. Using the 6" wide works as I found out helping skin a 1/6th scale round nose years ago

 

[Mike Cathey]

You are going to need fill and sand the 1 mm birch ply (which you can get from B&D Plywood in Tacoma and has 3 layers with marine glue bonding the layers) before laying the doorskin. The birch has to be pretty much perfect before you lay down the mahogany because the doorskin is so thin that anything but the lightest sanding will burn through it. Bending a piece of light music wire over the deck from side to side in several places will indicate high and low spots to fill and sand the birch ply. You can try some of the softening techniques above or cut the skin oversize and dry test it to see if it will lay down. The real boats all had lots of seams so if you need to do that it would be authentic. Wesley's Custom Graphics had some really nice simulated aluminum rub rail to lay down around the edges.

 

[Roy Munoz]

I used 1/64 veneer mahogany I bought from a local lumber yard. It came in 2' x 4' foot sheets.. I used Well-wood to glue it the the hull. I marked a C/L down the center of the hull and layed one sheet down to mark where it would lay first before painting the glue and trimmed excess leaving an inch around the hull. The second sheet will have to be trimed at the C/L to comform to the first sheet..It will take a while to trim and adjust..But the 1/64 is a bit easier to bend to the hull...

 

[Grimracer]

Check Aircraft spruce for 45deg mahogany. Never the less you will use a few cuts in the sheet to make the deck fit.. so you know the real boat has more then one sheet fit too.

But.. the 45Deg maho is very nice.

Mike

 

[Larry K]

Hey Steve! Welcome to IW!

For your consideration - I built the '57 Miss Wahoo in the '80s (twice!). My partner in crime and in boat racing, Ken Haugen had his own body shop. I had finished up a Shanty hull for him from the same set of Les Ruggles plans & when I asked him about paint work on the Wahoo, he said he could paint the hull so it would look like mahoghany. Amazingly enough, it turned out pretty nice. The ultimate compliment to his abilities came one day when another boater actually argued with me - telling me it looked too much like real wood to be paint!

Anyway, it is another option & you might want to talk to a couple painters - who knows, you might find someone willing to try it!

Larry K

 

[My Gypsy]

Larry,

Is there any chance you still have those Les Ruggles plans?

Dennis

 

[Larry K]

Dennis - Yes I do! I even have a jig that Les built! Rather than hi-jack this thread, you can message me at [email protected].

Steve - The curves on boats from the '50s are pretty severe. I would recommend decking the boat with 1.5mm/ 1/16in birch ply as thinner stuff may pucker worse and also require more battens to keep it from drooping between frames. I used 1/4" x 1/2" hardwood strips & screwed the decking to the frame-work starting up by the front and side of the engine well. The next strip, about 6" long, needs to go on the sheer about midway between the bow & sponson transom with some of the pucker toward the rear & some toward the front. Then just work your way to the corners. You're still going to have to skim coat w/ bondo & block sand but at least you will have some material to work with. After all that, then you can paint it as we did or use veneer to get the look you want. There is some pretty nice stuff out there. About ten years ago I found some mahoghany veneer with a thin backing on it at a hardware/ woodworking store. When I decked the Wahoo, I had a separate piece from the firewall to the transom - that joint at the firewall was the first place the paint cracked. Since then I've done decks in 2 pieces - "stem-to-stern" on both sides. Just leave some extra width & length on the afterplane decking and let it float until the front is screwed (or even glued) down. Remember - the framework MUST be attached to a jig or strapped down on a true surface before gluing the decks. It's those last "skins" that make the hull rigid!