Steam Launch: Wood – Displacement – Top load

[Ken S.Participant @kens-57619]

Hello group:

Looking at a project to fill out my approaching retirement and have selected a model open steam launch. Time won't be an issue. I 'll have a lot of questions about the lathe/mill work for the steam engine and the capabilities of my little Unimat. I'm posting these on Model Engineer's forum site. I intend to use the the Stuart twin steam launch combined with my own boiler build, water pump and condensate collector. I'm roughing out the conceptual design and layout and will post questions in the appropriate sub-forums.

I would like to get an estimate on size of the launch, beam, draft, hull thickness, wood type, etc that would be necessary to accommodate the mechanical devices, and maybe a water tank, unless I opt for pond water feed. I'm thinking 36"-48", closer to the latter, but not sure of other dimensions. Are their any useful readings on figuring model nautical dimensions.

When I put it in the water, I want it to go forward not dive like a submarine. Thank you.

From the other side of the pond.

Ken S.

NYC-USA

[Ken S.Participant @kens-57619]

[Malcolm FraryParticipant @malcolmfrary95515]

Knowing the overall dimensions underwater is only a small first step. You also need to know the shape of the thing. There isn't a set formula because all boats are a different shape (but something like 20-30% of that volume is a starting guess). If you have section profiles you can work out the area of each one. Knowing the distance between the profiles allows working out the volume of each section.

Knowing the volume lets you convert to displaced weight. This can help with working out the payload once you know what the rest of the boat will weigh. Then you can start to ponder over where the weight will go so that the boat not only sits in the water looking right, but also stays upright.

[Dave MilbournParticipant @davemilbourn48782]

Ken

My approach would be to have look through the available plans and kits for models of this type. You could then chose one of those or design your own model around the basic size and shape of the one you like most. If you stick closely to the thickness and type of materials they use then you won't go far wrong. You'd have to make an incredibly thick hull from a very dense wood before you would need start worrying about it sinking.
Here's a link to some plans – doubtless more are available elsewhere, too **LINK**

Dave M

[Tony HadleyParticipant @tonyhadley]

There is a build of an open steam launch on the rcgroups site. Based on the Puffin Muffin design which is on the list suggested by Dave Milbourn.

**LINK**

If the original magazine article on the 56" Puffin Muffin would be of any help, send your email in a message and I will scan.

Tony

[Ken S.Participant @kens-57619]

Guys:

Thanks for the info and links. Started to review them.

Regards,

Ken S.

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