Barrel Zip

Questions about modifying a design

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BarnacleMike
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Re: Barrel Zip

Post by BarnacleMike » Wed Jun 10, 2015 7:46 pm

Kudos to you for blending Riva lines with the Zip!

I've always felt that the Zip has more attractive lines than the Scoiattolo, though some would consider that heresy.

I have wondered if it would be possible to put a bit more tumblehome in the Zip transom, also. I had considered modifying the transom lines to have a similar shape as the Squirt, in order to achieve something similar.... However, I was concerned about the plywood making such a bend from there forward to frame #2.

I am very curious to see how your project progresses. The 3D rendering looks great!
-Michael

"How long does it take to build a boat? Until it's finished" — yours truly

Blog (Utility & Zip): http://barnaclemikeboats.blogspot.com/
Website of Boat Photos: https://michaelsmaddox.wordpress.com

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gap998
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Re: Barrel Zip

Post by gap998 » Thu Jun 11, 2015 1:48 am

Thanks Mike,

I agree the Zip proportions are pretty much perfect & there's nothing wrong with the standard stern; I just cant resist tweaking!

It's going to be a while before I get started, as I've a lot of jobs to get done around the house before I can get things rolling. Plus I still haven't decided whether or not to go straight to an Overniter & skip the Zip (i'm working on the Overniter CAD now & will post that soon too). Either way I'm going to model up the standard design properly from the plans first, and modify from there to see what needs to be done to the other frames. I'll post all progress as it may be interesting to see the boat in virtual construction before the physical build.
Gary

Planning a whole fleet, but starting with a Zip...I think.

"Just when you think you've made something idiot-proof, someone builds a better idiot!"

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gap998
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Re: Barrel Zip

Post by gap998 » Mon Oct 26, 2015 2:21 pm

Zip Plans Ordered!

Finally got permission from my wife to order the plans - she said I could have them as a birthday present. Still loads to do around the house before I can start though. In the mean time I will start a thread for a virtual build when the plans arrive, of first the standard Zip & then my modified Barrel-back design. hopefully it should prep me for the actual build and generate some clear visuals which should help other Zip builders.
Gary

Planning a whole fleet, but starting with a Zip...I think.

"Just when you think you've made something idiot-proof, someone builds a better idiot!"

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Gayle Brantuk
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Re: Barrel Zip

Post by Gayle Brantuk » Thu Oct 29, 2015 8:38 am

Very nice, Gary. I love the creativity and the 3D rendering is beautiful.

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vupilot
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Re: Barrel Zip

Post by vupilot » Thu Oct 29, 2015 6:04 pm

Barnacle Mike,

In my experience the Zip built as designed has just about the maximum tumblehome that can be bent with the ply thickness specified in the plans. Anything more is going to require modification to the material and/or assembly method.

Gap998,

Love the idea and rendering. Will make for a extremely attractive looking boat. Where there is a will there is a way, with the proper engineering this can be done, good luck!

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Dave Grason
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Re: Barrel Zip

Post by Dave Grason » Thu Oct 29, 2015 8:18 pm

Gary, I have a question. How difficult was it to render your Zip idea in the CAD program?

The reason i ask is that, for a long time, I have visualized the Bolero built with a deck and windshield that takes it's styling cues from a Donzi Sweet 16. But I've always wondered how it would look to have the boat painted below the waterline and above the sheer in a color of choice AND the topsides between the waterline and the sheer finished bright with Genuine Mahogany. This would be just the opposite of a traditional boat that used a combination of paint and brightwork. Whattaya think?

vupilot wrote:In my experience the Zip built as designed has just about the maximum tumblehome that can be bent with the ply thickness specified in the plans. Anything more is going to require modification to the material and/or assembly method.
AGREED!!

Yeah, the only way you would get more tumble home would be to cold mold the hull like Roberta, the QUEEN of the boatbuilders said. It sure would look DANG cool!
Isn't it amazing!! The person that never has the fortitude to pursue his own dreams, will be the first to try and discourage you from pursuing yours.

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gap998
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Re: Barrel Zip

Post by gap998 » Fri Oct 30, 2015 3:11 pm

Thanks for the complements guys - One of the reasons for for this build is to try out some modifications on a small scale for later builds. For the tumblehome I'm planning to try two layers of thinner ply over battens at the stern if the single wont go (I will be modifying the frame forward of the transom to graduate the curve).

Dave,

For the CAD models I screen-grabbed the catalogue line drawings, imported them into Autodesk Inventor and projected them into a 3D sketch, from which I generated surfaces and then thickened to solids. From there you can modify & colour. It was a bit of a learning curve, as I don't normally work with surfaces in my job; still it was an interesting exercise. It is quite time consuming though so for a colour scheme I would go for just a 2D line sketch & colour it up.

I think the Bolero & Bandido are great shapes which are ripe for some Van Dam style classic/modern fusion designs - If I live long enough, maybe a classic style Thunderchick/Bandido Mediterranean cruiser? :lol:
Gary

Planning a whole fleet, but starting with a Zip...I think.

"Just when you think you've made something idiot-proof, someone builds a better idiot!"

ToddM
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Re: Barrel Zip

Post by ToddM » Mon May 08, 2017 6:16 pm

Hi,

I am going to build a barrelback. That was not easy to say/write. I have long admired Chris Craft type runabouts from the 20's through the 50's, but have never considered building one because they look quite complicated, I have less than no experience with boatbuilding, and it never occurred to me that there might be existent plans to build such a boat. I am an amateur woodworker, and the other day while looking at a youtube page, up pops a video on building something called a Zip. It turns out that there are more than a few plans for building the type of boat I admire, and there are more types of that boat than I knew existed. And I like the barrelback the most. And today I saw a photo of a Riva Ariston.

So, now to my point. I want to build the Glen-l barrelback 19, but with the transom/stern/rear of the Ariston. My initial thoughts were to modify the rear most, (stern most?) frame to accommodate the change, but when looking at the side view from the study plans I ordered, it would be much easier to lengthen the bottom of the transom framing, and (fair?) the top of the transom in a more rounded fashion. Please forgive me if I am messing up the vocabulary, but again, I have no experience with boats or boat building. My question is, can I modify the transom with the easier method I described, or will that effect some operating, safety, or performance feature of the boat?

I use CAD programs at work, and I use CAD at home to design furniture and house remodeling, so I am guessing I can use the dimensions from Glen-l plans to draw up the modification. I tried to look at Michael's boatbuilding blog to see his CAD drawing, but was unable to find that particular post. What year and month did Michael post his CAD drawing of the his modification on his blog?

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Roberta
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Re: Barrel Zip

Post by Roberta » Tue May 09, 2017 4:59 am

The Tahoe 19 might be closer to your needs rather than trying to modify the Barrel Back plans. It wouldn't be that hard to round over the aft framing a little more to get that look.

Roberta
Roberta "Queen of the Boat Builders"
Built Zip "Oliver IV", Super Spartan "Jimmy 70", and Torpedo "The Glen L".

ToddM
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Re: Barrel Zip

Post by ToddM » Tue May 09, 2017 7:30 am

Thanks Roberta. Are you suggesting the Tahoe 19 because the "tumbledown" is similar to the Riva Ariston? And, am I using the term "tumbledown" correctly? I actually like the engine layout in the Tahoe 19 more than Barrelback, because It would seem to my thoroughly uneducated in boats mind, that locating the engine more towards the middle would distribute the weight better and necessitate less angle for the propeller shaft. Is that an irrelevant consideration? Does the location of the engine make any difference to the safety or performance of the boat? What I like about the Barrelback is the rounded stern deck, the communal seating, and the long expanse of deck planking.

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Bill Edmundson
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Re: Barrel Zip

Post by Bill Edmundson » Tue May 09, 2017 8:48 am

Todd

Look at the link below. It is a step by step of building a Tahoe 19. The BB is exactly the same process.

Bill
Mini -Tug, KH Tahoe 19 & Bartender 24 - There can be no miracle recoveries without first screwing up.
Tahoe 19 Build

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Roberta
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Re: Barrel Zip

Post by Roberta » Tue May 09, 2017 9:40 am

The round back of the boats is called "Tumblehome". The barrel back boats are the extreme version of tumblehome. The Tahoe is a lesser version. The Tahoe lends itself better for aft swim platforms and is a more performance hull. The traditional barrel backs are more flat bottom and don't like the higher speeds that the deeper "V" hulls can attain. You could go to the 23 ft Tahoe and not put in the aft rumble seat. Or stay with the 19ft and skip the rumble seat. I you are planning on skiing, I would go for the 19ft Tahoe and add the swim platform. It does have some really nice deck lines, even with the aft seat. Or just build the traditional Barrel Back. Not always a good idea to stray from the plans.

Do check out Bill's build site. He is very skilled and can advise you on that build.

Re-positioning the motor from the original design can cause balance and performance issues.

Roberta
Roberta "Queen of the Boat Builders"
Built Zip "Oliver IV", Super Spartan "Jimmy 70", and Torpedo "The Glen L".

ToddM
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Re: Barrel Zip

Post by ToddM » Tue May 09, 2017 10:30 am

Bill, thanks. I have actually already looked at that link, a few times.

ToddM
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Re: Barrel Zip

Post by ToddM » Tue May 09, 2017 10:47 am

Roberta, again thanks. I think I now understand more of what the tumblehome is. I have no thoughts of changing the location of the engine. It just looked to me that the engine on the Tahoe is located more towards the middle of the boat than the Barrelback. And for no good or experienced reason, I assume that the engine on a smaller boat is better located in the middle rather than the back or front. I did some car racing when I was younger, and generally speaking, a car handles better when most of the weight is centered and lowered. Honestly, the performance capabilities of the boat are less important to me than the boats aesthetic appearance. That may sound sacrilegious to boat people, but I am not a boat person. I am a wood worker and these boats are beautiful woodworking, besides being boats.

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Roberta
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Re: Barrel Zip

Post by Roberta » Tue May 09, 2017 11:01 am

They are beautiful and can be works of art.

Motor locations are designed with center of buoyancy in mind. Center of balance is different than center of buoyancy. As the hull shape changes, the buoyancy changes and to get the boat to float on the designed waterline, the center of buoyancy must be as designed. So it is important to stay withing specs .

Roberta
Roberta "Queen of the Boat Builders"
Built Zip "Oliver IV", Super Spartan "Jimmy 70", and Torpedo "The Glen L".

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