Old Dumas Hydro Kit... Many Questions!

[xraycajun]

Hey Guys...

The reason I'm posting here is that I'm sure y'all have had a alot of experience building in wood. Yesterday, I was given and old wooden Unlimited Hydro kit by a gentleman who was about to discard it for lack of time. The decals provided are for the mid-80's Miller American. I am assuming this is an old Dumas kit, as I remember seeing one in thier catalogue when I was a kid. Here's a list of what was in the box of parts:

Bulkheads - all die cut, many still not liberated from thier "parts tree"

sides of hull and sponsons - I figure they would put the model about 44" long

One sheet of decals - badly damaged

Plywood hull skin - all appear to be present

Two flattened stainless rods - I think they are for the fins, or they could be used to attach the cowl to the boat - like the way a slot car body attaches to its chassis.

One small aluminum tube - Shaft Tube?


There are no plans or instructions, so here is the first series of many, many questions I will be asking:

1) Is anyone out there familiar with the kit? Would there be a source for the plans or instructions?

2) I am guessing it's 1/8 scale, can anyone confirm this?

3) If hardware is still available, were can I find it? I checked Tower Hobbies but they seem to not carry the hardware that they used to.

I plan to spend my semester break cutting out the remaining bulkheads and test fitting to make sure none are missing. In the meantime, please notify me of any resources available to help me with this project...

Thank You All,

Xray

[Hydro Junkie]

For starters, take the die cut internal framing and use it for templates. The so called "mahogany plywood" isn't a good material for a hydro. For starters, it's very heavy as well as very porus. Replace it all with aircraft grade plywood from the local hobby shop or an online source. I would recommend 1/4 for the right sponson and hull transoms, 1/8th for the sponson insides, sponson lengthwise framing and the left sponson transom. Replace everything else that is cross hull with 1/16th ply. Be sure to get AIRCRAFT GRADE PLYWOOD, not lite ply. Also be sure that the 1/8th and 1/4 ply are FIVE PLY, not 3 ply. If the framing isn't set up for stringers, notch all the cross frames for 1/4 square SPRUCE stringers. These need to be installed anywhere a butt joint is called for involving the skin.
As for hardware, forget about the Dumas hardware package. There are many better product lines.
I would recommend getting a new decal set. I think you can get replacements from Dumas, or better yet, get them from Pacific Graphics at www.scalerc.com.
If you have any other questions, let me know, and I'll see if I can answer them

[xraycajun]

Wow,Hydro Junkie, you just created about 10,000 more questions in my mind!

I am guessing that this is indeed, and old Dumas kit, and that you have built it...
I will definately take your advice on the mahogany parts. I commented to myself upon inspecting them that they just don't seem sturdy enough for this size model. Many of they cross frames are ply instead of mahagony... i'll ask the hobby store if they are aircraft grade peices.

I'll start by templating, but I will need a better idea of what you mean by stringers. Are you talking about motor mount stringers? I'm a little confused in that area. This is where plans or instructions would come in handy.

By the way, Let me describe my intentions for this project. There are no clubs racing down here, so she'll never see single heat. I plan to run the 'gal strictly for sport. I would be very happy with a top speed of 30-35 mph and wondering if, for my purposes, I could get away with something smaller that a .67 engine.... maybe something with a pull start? I'll take your advice on the hardware... I saw it on the Dumas web site and was not impressed...

Thanks Dude,

Xray

[Hydro Junkie]

Haven't built that kit, but it's probably much the same as the 30" Pay N' Pak and 36" Atlas Van Lines. I wouldn't recommend going with less than a .45, if that would even get it up on plane.
Stringers are basically long continuous pieces of stick stock used to strengthen the lengthwise frames and give more to epoxy the skin to.

[xraycajun]

Ok,

I looked over the parts again and I see a 1/4" notch on both sides of each bulkhead.. I can see what your talking about now... I emailed dumas in an attempt to find plans and instructions. No reply yet.

Thanks,

Xray

[ososlow]

I am almost positive the boat is 1/8th scale.
Wait, here is a site that is in german: http://www.hydromarine.de/hm_20668.htm
Use this to translate what little there is to translate http://www.freetranslation.com/web.htm

My cousin has built 2 of these boats and still owns one done up just like on the box. Pretty slick looking boat. I couldn't tell you what hardware he used though. But I am pretty sure he ordered all his stuff from Dumas and he used the supplied wood. :confused:

Have fun and good luck :)

[xraycajun]

I managed to contact Dumas and confirm the kit came from them. I ordered the plans and instructions form them as well. The kit is old and the wood is very brittle. I figured out that it will only cost about $50.00 to upgrade the framework with 5-ply. I am going to do this because of the poor condition of the kit's wood.

I do have several more questions....

1) What epoxy, finishing resin, primer, and paint combo will work together? By this, I mean I want a good combo of glues and paints that won't chemically attack each other... and fuelproof, of course.... I'm planning on Z-Poxy for the glue... undecided on the rest....

2) It will only cost a few dollars extra to cut all the bulkheads out of 1/8" 5-ply. The kit's bulkheads are already 1/8, but the mahagony ply appears to be lighter. Anyway, will the extra weight of 5-ply bulkheads severely inhibit performance? (Keep in mind that I don't intend to race and that I want durability and reliability over speed)

3) I am not pleased with the kit's wing construction. If I were to form wings out of thick balsa sheets and glass them with thin fiberglass, won't that work just as well?

4) Were can I find the fiberglass cloth?

[abx131]

Most auto parts stores sell all the fiberglass stuff you need. It is readily available.

[Hydro Junkie]

I will say it again, USE 1/16TH PLY WHERE EVER POSSIBLE!!!!!!!!!!!!!!!!!!!!!!! The aircraft grade ply is just as strong as the Dumas 1/8th, so using 1/8th for all the frames isn't needed or desirable. All the extra weight will do is slow down the boat and make what ever engine you use work that much harder and wear it out that much faster. As for epoxy, I use and recommend West systems. It's more expensive than most of the other brands, but it's made for marine use. West Systems also makes fillers and strengtheners to work with their epoxy system.

[xraycajun]

Ok, I get what you are saying about the 1/16 ply. You did'nt specify 3 or 5 ply for that... Would there be be much difference? I did check out the West Systems website. I'm confident I'll use their products when I get to that point. I built the rear wing today. It came out much better than I expected it would. I've now got the confidence to really go after this project now...

Xray

[Hydro Junkie]

The 1/16th only comes in 3 ply, which is why I didn't specify the amount of plys to get.

[suck my wake]

sorry to hijack this thread. but hydro how far along is your boat

[Hydro Junkie]

Been buying hardware and a Futaba 9C Super with digital servos. Just haven't had the time to put any of it in yet. Still have to get a rudder, skid fin and bracket, as well as engine mounts. I guess that's what happens when you renovate half the house while building a boat, the boat has to wait :(

[xraycajun]

I got the fins and wing built. Moving on to the cowl now... I built the frame jig, too.. hope to be starting on the frame towards the end of July...


Xray