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Re: DetroiTug's Tug is going together

Posted: Tue Feb 26, 2013 4:49 pm
by DetroiTug
Center of what? I just keep screwing things on and keep a life jacket handy :D

All the railings combined probably total less than 20 pounds.

Iron Chief is a bit deceiving, it looks top heavy, but it isn't. The wood in the cabin sides is only 3/8" thick. The cabin roofs are 1/2" thick. The hull weighs around 1500 pounds and the Engine and boiler are roughly another 1500 pounds. Plus it has an 8' beam. I'm guessing the total weight to be somewhere around 4500 to 5000 pounds and 75% of that is below the gunwale. This style hull/boat was never intended for rough water although they handle it quite well.

There are some interesting and informative articles around the web on hull stability. The common practice or thought on improving stability is to add weight low, that is accurate, but incomplete. Adding any weight to a multi-chined hull and others, even above the gunwale within reason, improves stability. The deeper the hull sits in the water the displacement is increased -center of buoyancy is raised and there is more wetted hull surface/shape working towards greater stability. Pointing to some of these cruise ships, looking at them straight on, they appear to defy physics. The designers have added enough weight for the hull to work properly. More weight makes it a bigger hull in the water. Where this is really noticeable, when I there are ten er so people aboard. Someone steps on the gunwale, it doesn't budge.

Here is a video in some rough water and we went out further and the waves got even bigger and we ran them on the same tack. It rocked around pretty good, but any 22' boat would. It went down on the rails a few times and always came back.



-Ron

Re: DetroiTug's Tug is going together

Posted: Tue Feb 26, 2013 5:26 pm
by Lopez Mike
True that ultimate stability isn't arrived at by a low C.G. alone. I have a number of power boats and sailboats and have dealt with all of that many times. Also, you have a lot more power than I do.

I am trying to keep my hull weight down just to to save fuel, increase performance and cut down on the towing weight. Folly probably weighs around 1500 pounds right now. Certainly less than 2000. And maybe five H.P.

I'm having trouble finding a good set of lines. I like the basic numbers of what I have now. 24' x 6' with a plumb bow and a small transom. Lots of room for a decent wheel. Straight along the bottom for easy loading and unloading.

What is wrong with my boat now aside from being poorly built of bad materials is that it is as ugly as a singed cat. The sheer is "straight". That is to say, it averages to a straight line. There are places that go up and down an inch within a foot of two. The sides are vertical. Looks like a tanker designed to fit the Panama Canal. With dents. Dents in plywood? Well, shitty butt joints.

What I would like to find is a set of lines for a single or double chine hull that I can build either as stitch and glue or panels over frames. Around the size I have now. I steam in sometimes rowdy waters so not too low of freeboard.

Mike

Re: DetroiTug's Tug is going together

Posted: Tue Feb 26, 2013 6:51 pm
by DetroiTug
Mike,

The Panatella or the Parker hull that S. Weaver is building sounds about like what you are looking for.

S. Weaver's hull would be a good subject for steel as well.

Image

-Ron

Re: DetroiTug's Tug is going together

Posted: Tue Feb 26, 2013 6:59 pm
by Lopez Mike
Ron,
Thanks for reminding me about the Panatella. I'll look at it again. I remember thinking that it didn't have enough freeboard for Puget Sound waters but I never actually measured the lines to check my assumptions. It's certainly beautiful.
With my machinery and a max of four people, it would need to handle perhaps 1500 pounds. And I'm using a VFT boiler with a little higher C.G.
Wonder if a lightly built forward cabin and an aft canopy would sink it?
Mike

Re: DetroiTug's Tug is going together

Posted: Wed Feb 27, 2013 2:22 pm
by Rainer
Lopez Mike wrote:Also, Rainer,
Do you happen to know how much your new hull weighs at this stage of construction?
Mike
Hello Mike,
my Rami is 140 kg (309 pounds) now including dry paint ;-)
Estimated max "wet weight" is 400 kg plus two adult with provisions = 650 kg
With 730 kg (1609 pounds) it has 0.21 m (0.69") hull draft - excluding the prop.

- but all this with only 4.71 m (15.5") water line length and 1.47 m (4.8") water line width equal 5.6 m² (60 sq.ft.) weted surface - not comparable with your boats!

Ramis purpose is to act as an engineering platform for my new engine and to enable me to go to boat meets in Paris, France; Venice, Italy and Monaco. All this about 1000 km one way from home.

You can buy trailers here for a total weight of 750 kg (1653 pounds) equal 500 kg "payload". You can tow this with virtual every car in Europe and every (car) driver license. OK, I have an old license for up to 12 tons - but so you can give it to other people more easy.

Additional with such a small trailer you can increase the legal Autobahn speed from 50 mph (80 km/h) to 63 mph (100 km/h) still very slow compared with other traffic - OK...

Re: DetroiTug's Tug is going together

Posted: Wed Feb 27, 2013 4:53 pm
by Lopez Mike
Ranier,
I am so impressed at how well you have kept the weight down. Now I will certainly look at the Panatella lines more closely.
Are you planing any sort of cabin or top?
Mike

Re: DetroiTug's Tug is going together

Posted: Wed Feb 27, 2013 5:54 pm
by DetroiTug
Mike,

If you go back in this section of the forum to page 3? There are a few threads on a Panatella (Rushforth) built by Dave McAndrews? He widened his hull out a little bit for added stability.

What ever happened to him? He was a good poster, always had great input.

-Ron

Re: DetroiTug's Tug is going together

Posted: Wed Feb 27, 2013 6:17 pm
by Mike Rometer
Rainer wrote:Additional with such a small trailer you can increase the legal Autobahn speed from 50 mph (80 km/h) to 63 mph (100 km/h) still very slow compared with other traffic - OK...
A whole 63MPH, lucky you! In the UK that restriction would be 60MPH.

Re: DetroiTug's Tug is going together

Posted: Wed Feb 27, 2013 8:30 pm
by fredrosse
When driving the sidewheeler to New England, the Lees Mills NH meet, I am constantly having my "80 MPH Alarm" going off, and I am basically just keeping with traffic, that is a little over 125 kM/hr. My 4.0 liter Ford Explorer could barely make 80MPH with the trailer, but my 3.0 liter X5 has no trouble here, the only possible problen is that it is easy to forget you are towing a trailer.

Re: DetroiTug's Tug is going together

Posted: Wed Feb 27, 2013 10:30 pm
by Mike Rometer
fredrosse wrote:Snip . . . the only possible problen is that it is easy to forget you are towing a trailer.
And keeping an eye out for the 'Smokies'!

:lol: :lol: :lol: