Scratch building a 1/8 Hydro (Full Version)

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thevirginian -> Scratch building a 1/8 Hydro (12/2/2007 10:34:49 PM)

After completing my design in CAD a decided to build a model of the boat using balsa wood only. I thought if I run into a problem I can easily alter the plans before I go with ply wood and fiberglass. The progress in building the balsa model was fast and without any glitches. I did find a couple areas where I made changes to the original plans, though. Now, since everything seems to fit my likings I am determined to purchase the plywood sheets and start with the real thing soon. But before I am going to do that, I still have to make the cowling. I will show the method I have chosen how to build the cowling once I got started. For right now here are some pictures of my balsa model.



martno1fan -> RE: Scratch building a 1/8 Hydro (12/2/2007 10:50:48 PM)

nice boat mate what plans did you use how big is it? ,if that were mine id stick a nitro motor or brushless electric motor in it and get it wet.you could go gas if you glass the whole thing using glass cloth .ive used glass cloth over balsa before on big sailboats and it works great.might save you some building and get you on the water faster [;)].



thevirginian -> RE: Scratch building a 1/8 Hydro (12/3/2007 12:42:58 PM)

martno1fan,
Despite several opposing comments from RCU boat fans in this forum I designed the boat myself on CAD. What you said about glassing the balsa hull with glass I had in mind before. I strip built several sailboats from balsa znd glassed them. Difference is a hydro is subjected to a lot more stress then a sailboat. I am planning to put either a Zen 26 or Sikk 27 in it. The measurements are 43.5x23". I promised the balsa model a buddy of mine. He wants to glass her and power it with electric. I posted my plans below.



Dana W -> RE: Scratch building a 1/8 Hydro (12/3/2007 1:06:31 PM)

Nice job . Nice to have a CAD as well .



martno1fan -> RE: Scratch building a 1/8 Hydro (12/3/2007 1:39:10 PM)

i dont see a problem using that hull if you glass it mate its no diff than having a glass hull exept you will have youres lined with wood and looking nice on the inside [;)].Just make sure you lay the glass thick enough to handle the rigours of running a gas motor.The plans look good i have a few similar on a smaller scale.how did you get those plans printed full size? print shop?.



webdr -> RE: Scratch building a 1/8 Hydro (12/3/2007 3:40:04 PM)

Incredible work brother!

Looks like you have good grasp of what your doing, what opposition did you get from the masses?



thevirginian -> RE: Scratch building a 1/8 Hydro (12/3/2007 4:57:49 PM)

Thanks for the laurels, guys
martno1fan;
I know what you're saying. You absolutely correct. I could have made it to be glassed afterwards. But I didn't use 1/4 ply for the motor stringers. Also no ply for the transom. My intension was to build a balsa model quickly to see what the outlines are in real life. I could have designed it using a 3D software I also work with, but I am a more of a hands on type of guy, if you know what I mean. And to honest this model was done in no time. I started last sunday and she is basically done by now. I did get inspired by "Hydro Junkie". He seems to be a great builder. I used AutoCad for designing my plans and have the luxury of a large plotter. So I can plot full scale. Like I mentioned in my previous post I made some changes on the model, which I implemented into my plans, afterwards. The other reason for using plywood is that the boat will be straighter and truer compared to balsa. Unless I would have used more bulkheads and stringers.
webdr;
If I start a project such as this, I think I know what I am doing. Basically the only opposition was like "Do yourself a favour and buy some plans from Newton Marines". I didn't take it in a negative way, though. But designing and building a boat is no rocket sience. I have built several full scale boats, a couple model sailboats and two full scale kayaks. For me this project is no different. I will keep you guys posted with plenty of pictures and progress updates. But first I have to order teh plywood and get started with the real model.



martno1fan -> RE: Scratch building a 1/8 Hydro (12/3/2007 6:26:35 PM)

No worries mate im sure when you build the plywood one it will turn out even better ,after all youve had a practice run now [:D].Keep us posted mate im very keen to see how it turns out.Dont ever get put off by people saying you cant do it,i never have been [;)].



thevirginian -> RE: Scratch building a 1/8 Hydro (12/3/2007 10:14:39 PM)

martno1fan
you betcha. If somebody tells me "you can't do that", it's even more of a challenge for me.



chief3452 -> RE: Scratch building a 1/8 Hydro (12/3/2007 11:39:38 PM)

Hey Virginian,

Mock up model looks like a winner! Can't wait to see what comes next. I wish I had access to all those great design tools you have, must be nice. My hydro is plodding along too. I'm curious where you came up with your dimensions for your sponson riding surfaces, I am trying to figure out what would be a good width of ride pad to do on my boat. http://www.rcuniverse.com/forum/m_6574785/tm.htm Appreciate any input you could provide, thanks.

Scott



Hydro Junkie -> RE: Scratch building a 1/8 Hydro (12/3/2007 11:54:33 PM)

Time for a suggestion session. There are some changes I would make when you do your plywood hull:
1) Raise the ramwing and round it off, adjusting the bottom angle accordingly
2) Leave the center open for the full length of the hull
3) Let the center of the sponson bottom run slightly below the side panels
4) Use the following materials in these locations:
1) 1/4 aircraft ply for the right sponson and rear transoms
2) 1/8th aircraft ply for the sponson insides, engine bay walls, sponson sheers and left sponson transom
3) 1/16th aircraft ply for everything else
5) Plan on a 7" engine bay width to allow room for the carb and exhaust header rather than trying to run them both out over the deck



dwr9 -> RE: Scratch building a 1/8 Hydro (12/4/2007 12:27:27 AM)

Looks great. Keep posting pics as you work on it. Doug



thevirginian -> RE: Scratch building a 1/8 Hydro (12/4/2007 1:07:20 AM)

Hey, chief;
I admire your shovelnose very much. Looks really great. For my sponsons I kinda copied what I thought was alright on an 'Insane' Hydro a buddy of mine races. I don't think I am going to be too far off. Yeah, good computer software sure is a great help in designing stuff like that. I will keep you guys posted.
Hydro Junkie;
I appreciate your input very much. I can imagine you are an expert in this class of boats. Let me ask you a few questions regarding your comments: Why do you think the ramwing is too sharp and too low? I am not disputing your suggestion. I am just curious. Could you elaborate on your second and third suggestion a little bit more? Regarding the plywood thickness, that's exactly what I had planned to use.
Thanks for your help



Hydro Junkie -> RE: Scratch building a 1/8 Hydro (12/4/2007 1:25:22 AM)

On the ramwing, as low as yours is, you will be taking a lot of water over it. By rounding it off, it will be more aerodynamic than a sharp edge and not so likely to get damaged if you hit something
On leaving the center section open, it will make running and repairing drive gear, cooliing lines and pushrods. it will also make getting any water that gets in there easier to get out
On dropping the center of the sponson down slightly, it will prevent the water from sucking your boat down. With the flush joints between the bottom and sloping sides, your boat will have a hard time getting up on plane since the water will have more surface area to grab. By dropping the center section and keeping the edges sharp and at approximately 90*, the water will have less to grab. This will result in better handling and more speed.



Strikar -> RE: Scratch building a 1/8 Hydro (12/4/2007 2:14:29 AM)

Nice looking model, and great CAD skills.
I see a bright future for you in CAD.



thevirginian -> RE: Scratch building a 1/8 Hydro (12/4/2007 12:50:23 PM)

Hey Junkie;
Guess what, I had the ramwing rounder before but then sharpend it for less resistance. But I will heed your advise and make the necessary changes. The real boat will have an open deck. Only one small section will be covered. How much do you think I should build up the bottom of the sponsons? Another 1/8", perhaps? On the real boat I was going to add another 1/16" ply on to it and sand it slightly so it angles slightly to the outsides. Yes I will keep the edges sharp. But like I said before: I will test run the boat before I put the finishing coats and touches on her.
Hey, Strikar
thanks for your incouraging comments. I had to smile regarding my "bright" future in CAD. I 've been doing AutoCad since 1991 and I am way past any future prospects in my carrier. But I do have a nice position and hopefully can hold on to it until I retire [;)]



chief3452 -> RE: Scratch building a 1/8 Hydro (12/4/2007 1:45:16 PM)

Hey Virginian,

Can you tell me how wide your sponson ride pads are? Sorry if you mentioned it before, also what are the overall dimensions of your hull. Have you started cutting plywood yet for the real model? Thanks,

Scott



Proboat 772 -> RE: Scratch building a 1/8 Hydro (12/4/2007 3:26:10 PM)

Virginian

Your design looks very sharp. Hydro Junkie gave you some good pointers to refine the hull. For what it is worth, here is a template of the 1/8 Bud sponson to give you a starting point.

Dick T.



thevirginian -> RE: Scratch building a 1/8 Hydro (12/5/2007 12:49:17 AM)

Hey chief,
Here are my measurements again: length = 45", width= 24" , sponsons are 2.625 wide and 19.75" long. The height of the step is 1/4". Other than that the spnsons are very similar to the template proboat posted (thanks propboat). No, I have not started cutting plywood yet. But I purchased a brandnew Craftsman 16" Scrollsaw today. Was on sale for $99.99 minus another $10 discount. Couldn't have passed up that deal. I am still fiddling around fine tuning my plans. I want a boat that will turn out to be perfect. I am kinda perfectionist. I am going to order all the plywood tomorrow and once received get going. Untill then you guys need to be patient. I will post plenty of pictures and tell ou about my building progress.



thevirginian -> RE: Scratch building a 1/8 Hydro (12/5/2007 12:52:16 AM)

Hello chief,
I have to correct myself. The sponsons are 6" wide and 19.75 long. Only the very bottom step is 2.625" wide. Sorry about any confusion.



Hydro Junkie -> RE: Scratch building a 1/8 Hydro (12/5/2007 12:55:06 AM)

Proboat772, that looks like the right sponson, the left should be a totally different shape. Is that off a Pro Boat Bud or an actual scale boat?



chief3452 -> RE: Scratch building a 1/8 Hydro (12/5/2007 1:30:52 AM)

Hey Virginian,

thanks for the info. Much appreciated. Smokin' deal on the saw too. Can't wait to see your build thread.

Scott



Strikar -> RE: Scratch building a 1/8 Hydro (12/5/2007 2:33:35 AM)

Sorry man, I read "after completing my design studies in CAD" some how, hehe [:D]



Proboat 772 -> RE: Scratch building a 1/8 Hydro (12/5/2007 2:47:01 AM)

Hydro junkie,


That was a template off the Proboat Bud, Llumar etc. left sponson at the transom end.

I can't check the other side as the boat is up North and I'm in Florida.

I believe both left and right sponsons are similar but can't be sure.



thevirginian -> RE: Scratch building a 1/8 Hydro (12/5/2007 1:56:39 PM)

I 'll check the sponsons of my buddie's "Insane" Hydro tonight, to see if they are different. One thing I know for sure: Insane Hydros don't have that step on the bottom of their sponsons. I was a bit surprised about that already.



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