boat building

**TTriton** · 05-27-2001, 09:35 PM

Does anyone have a source for plans on building a STV type boat? I've been looking at picture of F1 boats and other STV's , Mirages, and Noah's great looking Cyclone 182 to get idea on designing my own boat for PERSONAL use. I don't plan to build them for profit. I just want to build something of my own. But I think that the plans to another boat would great help me in this endever. I could get ideas from it or modify the design to make my own thing. Or maybe just make one the way the plans say then work on my own design with the experiance that I gained from making a boat from someone else's plans. And I'm not looking to spend a bunch of money for the plans but am willing to buy them. THanks for anyone's help. And I'm looking to build a 18 to 20 foot boat. That I can put a Merc 200 on. I'm not looking to go extreamly fast I just want a boat that handles like a F1.

**Techno** · 05-28-2001, 08:03 AM

What you should do is add up the materials and see if you can do it cheaper. With no mold you'll have to build the boat similar to a wooden boat, frames and skin to support the shape. Although you can remove the frames the skin would be very difficult to remove. Also this shape boat is difficult to build (compared to a Vee hull). There are alot of angles and level changes.
If you build a mold there's no comparison, It'll cost way too high.
Heres a few views of the bottom courtesy of Euroski
http://www.microconnect.net/~pcpower/hotboat.htm
And probably the most important. You build it and it doesn't perform like what the boat should.

Theres a few builders that build a boat that I think is cheap(meaning economical not garbage). Unlike the big boat builders you can order a boat from them just about like you want, completely bare, partially rigged, fully rigged, bear cooler installed, extra braces whatever.

**Scott** · 05-29-2001, 09:06 PM

I know a guy that collects hulls. He's the one I got my Baja from. He won't take them unless they'er in good shape but all need some work, some more than others. My Baja for example was faded badly with more than a good chance the transom is in need of replacement. The hull is solid w/ no cracks but alot of digs and dings. No interrior and what rigging did exist is shot. Almost like starting from scratch?? We can "re"make it the way we want, better than the original but w/o the expense of building a hull. With a family I took the Baja for it's ability to fit somewhere inbetween a two person screamer and a barge. I think we can make it fly and still carry the kids to the island on occasion. It's been a great project, almost like building my own. He's probably got yer hull?

[Edited by Scott on 05-29-2001 at 09:09 PM]

**David_L6** · 05-30-2001, 12:36 PM

If you have the capability to build a wooden hul like you want, you should be able to build a mold, but WHY!? That's a LOT of work (either way - "just" a wooden hull or a plug and mold) and if you go so far as to build a mold a LOT of money too. If you don't have a LOT of time to devote to the project, you may not live long enough to pop the first hull out of the mold!

**Liqui-Fly** · 05-30-2001, 01:48 PM

There is a book and computer software called the Secrets Of Tunnel Boat Design that may be of assisstance to you. Wood core with a glass or kevelar skin would be a great way to build a "one-of". David

**TTriton** · 05-30-2001, 03:47 PM

I have my scale model almost done. I've looked into the book Secrets of tunnel hull design and I belive that I m going to order a copy. ANd I don't plan to build a mold. I plan to build a "one off" Any way I have enough molds. And if any one is interested in boat molds I have six differnt hulls that I'm trying to get rid of. But NON of them are tunnel or cat design. THey are all high performance hulls similar to a glasstron and some I guess are somewhat similar to a Action Craft flats boat but with a cap that is stricly a high performace design or ski boat. If anyone is interested let me know I want to get rid of them.

**Jimboat** · 05-30-2001, 05:02 PM

Check out web site http://www.aeromarineresearch.com

**Instigator** · 05-30-2001, 05:28 PM

You can definately do it yourself but, if you do glass you will have a ton of labor and money into materials!!
If you want to do your own, why not go wood?? A lot of/most of the builders start with a plywood prototype to see if their design works. It's a lot cheaper/easier to do than a mold/glass. It's also easier to chenge/modify your initial design.
I have the tunnel boat design book, and while it has been several years since I read it, it seems like it was aimed mostly at competition.
Most of the early (unsuccesfull) tunnel desins were copies of competition boats with no center pods. Be carefull!
On the wood issue, remember that most of the F-1 boats are still plywood! Awfully tuff to beat the strength to weight ratio of wood!
Clark Craft and Glen-L have some descent designs/plans although most of them are at leats 20 yrs out dated, and not much in tunnels.
Most boats are glass today because of the drastic reduction in assembly labor and lack of maintenance, not an increase in strength.
Also if you're working with scale models, be carefull with your conversion formulas it's not based directly on size. (speed vs, lift etc.)
Have fun with what ever you decide to do though!!
Instigator

**TTriton** · 05-30-2001, 05:36 PM

I've looked at most of those website and agree with you that all the plans are very out dated. And I'v already desided to go with a center pod and not a design that is so much like a compitition boat. The top of the boat will look more like a F1 boat to the untrained eye but will have three seats in a row and be longer than a F1 boat. I'm planning for a 20 foot boat. I'm not going for all out speed I just would like a boat that can handle really well and be in the 60's maybe low 70's with a merc 200 carb.

**Instigator** · 05-30-2001, 05:51 PM

I've got an old Mechanics Illustrated from I think the mid '70's where they built a competition tunnel boat and powered it with a stock OMC V-4 (I think) and ran almost 70 with it.
Seems like it was around 17'?? No pod but for what you want to do, I think you would be safe in "enlarging" their plans and adding a center pod and you might be there??
Let me know if you're interested, I can scan the article and e-mail it to you. It's about the only semi current design that I've seen.
Another option would be to find a local guy with a real one, give him a lawn chair and buy him beers and copy his??? Not that difficult to do.
I have built many plywood boats, and if you take your time you can make then look just like glass!
P.S. I know what you do for a living and my hats off to you!! I used to dock a cabin cruiser in a marina where there was a "Tow Boat US" operated out of and those guys had to have their boat prepared to and did go out in ANYTHING!! They have to run, peoples lives depend on you!
WAY COOL!
Instigator

**David_L6** · 05-30-2001, 05:54 PM

Yes, it is hard to beat the strength to weight ratio of wood. Wooden boats require a lot of maintanence though. My newest boat was built primariy of thin ( some of it on the order of 3 mm) plywood and overlaid with carbon fiber instead of 'glass. Lighter and stronger than wood alone and a lot lighter than 'glass. EXPENSIVE though.

I believe that I now understand what the original poster wants and I feel that wood is the way to go. If possible, build it as I said my boat is (carbon fiber over thin wood). Also, SEAL (West System epoxy) EVERYTHING as well as possible (double check it and seal it some more even if you have no doubts!).

Good luck.

p.s. I still wonder if you are a glutton for punishment!

**TTriton** · 05-30-2001, 08:48 PM

Yep thats me. I probably should ad some more information. Part of my reasoning is cost. I can't get $7,000 for a new hull but I have the time plus my family owns a marine store where I sell fibreglass cloths resigns and other marine items of the sort. SO that helps my cost. And I do have the time. IF I'm not working on a engine or out towing a boat I normally have time to kill. And I'll have help doing the work from other friends. And the big reason. I just want to build my own boat. I would like it to be my design but if I do it from a plan first o-well. Next time I'll do it all on my own. And then the next time I'll use carbonfibre. Which we also sell. But at my cost it is still to much for boat building right now.

**TTriton** · 05-30-2001, 09:46 PM

I have my scale model almost done. I've looked into the book Secrets of tunnel hull design and I belive that I m going to order a copy. ANd I don't plan to build a mold. I plan to build a "one off" Any way I have enough molds. And if any one is interested in boat molds I have six differnt hulls that I'm trying to get rid of. But NON of them are tunnel or cat design. THey are all high performance hulls similar to a glasstron and some I guess are somewhat similar to a Action Craft flats boat but with a cap that is stricly a high performace design or ski boat. If anyone is interested let me know I want to get rid of them.

**Jimboat** · 05-31-2001, 10:31 AM

I agree with "Instigator", that wood is definately your best bet. It's the easiest way to build the design configuration you really want, and can finish it to a beautiful looking surface. Glass is only good because it's easy to build production line boats, but it will always till much heavier than wood.

As for changing or modifying your initial design - that's where the Tunnel Boat Design Software can really help (see my web site). TBDP makes it easy to optimize your hull design and setup specifically for your operation and performance needs. Any changes you want to test can be tested with the software, without de-rigging the boat, cutting, gluing, painting and re-rigging.

The new software is equally applicable for commercial tunnels or modified tunnels with or without centre pods. I is based on the engineering principles in the new Secrets of Tunnel Boat Design book, but of course more detailled in it's analytical capabilities. Also allows for varying designs of centre pod to optimize performance. It's used at least as much by designers and builders of commercial and high performance pleasure boats, as it is for competitive racers. "Instigator" is also right that most of the early (unsuccesfull) tunnel designs were copies of other boats - and many didn't work at all. Most of the available designs are very old. Best rule I've found is that the designers that work well, aren't telling! Careful research is your best bet.

Good luck, and have fun!

/Jim
http://www.aeromarineresearch.com

**Instigator** · 06-01-2001, 09:07 AM

JIMBOAT, excellent response! My version of your book is probably 15 yrs old, and its been that long since I read it!!
TTRITON, I would also take Jimboats advice and start with something that works or is a known. Sounds like you can use his home work to test ideas and changes to see if your on the right path??
As far as building it yourself, I'm here to tell you that there is'nt much that is more satisfying than having it turn out well, look good, and run even better!
I have been on both sides of that too. Spent most of my time designing/building 9'- 10' hydroplanes that I raced in competition. The ones that I started with an existing design but modified, all worked very well.
I tried a tunnel boat that did not!!
I worked for a guy that was world champion in the Pro O/B classes and we built boats for all the guys that won. He instilled in me, a drive to be different, and to come up with my own desing like he did. (and sounds like you have)
Anyhow, we were all racing three point hydros at the time and driving on our knees when I decided to design/build a tunnel. Not just a tunnel, but I decided that I would make it a lay down boat. This of course, drastically lowers your center of gravity in the turns.
The boat came out bad to the bone! Best quality of work I had ever done! No putty anywhere! Looked like it was doing a hundred on the trailer.
Of course it did'nt work.
Many people (way smarter than me!) had tried and failed. And I knew it.
One of the reasons you drive the little boats on your knees is so you can put your ass against the motor board to get the boat to "float" out of the corners. By laying down I moved the center of gravity forard by 6 or 8 inches which of course glued the boat to the water.
So first desind change, drive on my knees.
I needed to run about 65 MPH's between the corners to be competitive in that class. That boat would run 64 1/2, but would not run 65. No matter what!!
I also built it about 6 inches to short, so it built lift "very suddenly". I knew most of this going into it and thought I could compensate by having supperior corner speed and acceleration.
WRONG!
I blew that little bastard over, three times!! I'd try and get it to float the bow at speed and it would run very flat at 64 1/2, at 65 you were looking at sky!!
After the third time, I towed it home, pulled off the motor and all the hardware. Then I put a 12" blade in a Sawz All and cut it into three peices and drug it out to the street and stacked it up for the trash!!!
Anyhow, I guess my point is that that was 4 sheets of plywood, some money, and a ton of time. I can't imagine if it was a "real boat"!!
I would also re-caution you on your use of scale models. Not sure what your thinking, but I thought I could tow a 1/4 scale model at 1/4 of the projected speed and get an accurate test. Don't think thats accurate??
P.S. If you have resin/glue mixxed up and applied and you get an emergency call, what do you do???
Don't think I'd want to get in trouble in your area till the boat's done!! (Hah,Hah!)
Good Luck!