Car Toppable Trimaran Pocket Cruiser

guzzis3 · Mar 26, 2021

It's a small project in the scheme of things. Materials are nothing compared to your time...if you were building a 40' cat that would be another bucket of fish...

kerosene · Apr 4, 2021

David L. Dodd II said: ↑

Okay, so I tried to make the model of my first amma today. The process is simple. Cut out two sides and make sure they are identical to each other. Glue the bottom of the two sides together with a fillet. Pull the bow together and glue. Force the whole thing through a form shaped like the deck. Glue the deck on. Instant amma.

I had Delft Ship run expansions on the tortured ply design for the ammas. Then I exported the expansions to illustrator and cleaned them up. I cut the expansions out of card stock. I glued the two halves of the hull together along the bottom, then I glued the bow together. As a result the model forms a shape that looks a little like a banana. At this point I looked at the hull and wondered to myself how this would look like the graceful amma I had drawn. Then I cut out the deck expansion and glued the card stock around the deck cutout to several more peices of card stock. Then I cut the shape of the deck out the additional piece of cardstock to produce the mold through which the ama needed to be forced. If things went to plan the shape of the hull would magically appear when I pushed the hull through the form. As expected it did not work, but it was close. My first model has a shape very similar to my drawings but there was not enough material in the forward sections, when the area between the bow and the midesction tried to spring into shape, a hollow appeared where the two sides joined. The Joint along the bottom also failed at several points. In the model, I just used elmers glue which wasn't strong enough. On a full scale version I would use an epoxy fillet with fiberglass tape. I redrew the expansions in illustrator and added a bit more material to the joint where the hollow was. In order to make the joint in the model stronger I am adding a peice of cardstock shaped to help the joint hold together. I then made the amma a little taller to help distribute the stress.

In addition, I have to add a curve from front to back to the form in order to mach the reverse sheer of the amma. Once I get a new amma built, using the new expansions, I hope to provide a photographic explanation of the process.
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you should get gougeon brothers’ book. (The Gougeon Brothers on Boat Construction: Wood and WEST System Materials). They created amas like you describe. It is a good book, I bought my 1st copy almost 30 years ago at 16.

in the book the pre bend the halves when they are glued together.

David L. Dodd II · Apr 4, 2021

Thank you for the suggestion. I have the book already, it is were I got the idea from.

kerosene · Apr 4, 2021

Silly me. That method has always intrigued me but intimidated also for its unpredictability.

Gary Curtis · Apr 5, 2021

Will Gilmore said: ↑

You could build your model out of non-marine exterior grade luan. I'll bet Covid has improved the business of home improvement companies. All those people working at home with extra time to work on that DIY project. Prices will still be up, because covid is a good excuse to rationalize higher prices, but not like the specialty wood supplies.
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You could try a Weta.

Will Gilmore · Apr 5, 2021

Gary Curtis said: ↑

You could try a Weta.
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David L. Dodd II · Apr 6, 2021

Will Gilmore said: ↑

View attachment 166957
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I wonder if those kids know how lucky they are

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Car Toppable Trimaran Pocket Cruiser

Is this a good idea

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guzzis3 Senior Member

kerosene Senior Member

David L. Dodd II Junior Member

kerosene Senior Member

Gary Curtis New Member

Will Gilmore Senior Member

David L. Dodd II Junior Member

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