Dinghy build from plan

[colhel]

I'm seriously considering having a go at making a simple plywood dinghy from a plan. But, we have a bit of a garden project going on where want a dinghy planter, so I thought I could use this as a practice, with cheaper materials. So my questions are, is it worth buying full size plans where, I assume, you lay the plan on wood, mark and cut round or buy an A4 version. If using a fullsize plan, is it likely they'll get damaged beyond use after one go?

 

[coopec]

If you are building a dinghy planter in ply use exterior quality ply. It will have knot holes but the glue will be the same as used in marine ply.
If you can't build from A4 plans maybe you shouldn't be tackling it.

Why not build in fiberglass?

 

[Graham376]

If you buy full sized plans and want to use them more than once, make templates from them and use the templates. No doubt you're going to have to upgrade the build anyway as all the design stresses will be reversed when filled with earth.

 

[colhel]

Okay, maybe I phrased the question wrong. I've built model aircraft from full-size plan and well used to engineering drawings. But I've never built a full-size boat. Therefore, is it worth spending the extra on a full-size plan and if so can it be used again.

 

[colhel]

If you buy full sized plans and want to use them more than once, make templates from them and use the templates.

Thank You. Obvious really ?

 

[coopec]

If you can build model aircraft surely you can build a dinghy by scaling up the plans?

If you are worried can you get large sheets of cardboard from a solar panel retailer and scale the drawing up?

 

[Daydream believer]

Are boat plans , even for a dinghy, ever full size?
As for materials, a school friend of mine built a pram dinghy out of oil tempered hardboard, in the wood working class. he actually played with it for some years. If one wants a cheap, quick to build dinghy, there are plans available & one really does not need to " practice" if one has a reasonable ability with a few basic tools. When finished I suppose you could coat it in UV resistant resin . Do not paint after as it adds weight.
. Keeping it as light as possible means that you are more likely to lift it out of the water rather than drag it. Thus less damage should occur. The trailer can be a piece of 150 * 50 timber with a couple of wheels & a piece of 50 * 50 as the central bar. A short handle at the front. A strap over the top holds it on.I tow my rubber dinghy home behind my bike on such a trailer.

 

[DownWest]

If you want more than a basic flatty, then look over at Classic Marine. The sell Iain Oughtred's plans and there are some very nice tender type dinghys there. Also The Wooden Boat Magazine sells plans for tenders too, among many others. The 7ft 6in Nutshell pram is a great littleboat. Tenders and Prams Plans
Jorden boats sell CNC kits for several boats. Just the ply, you find the rest.
I built a 15ft from Iain's board. The plans are works of art and you will not have any trouble.

And, John Welsford is highly respected in the ply boat market. John Welsford Small Craft Design

 

[Motor_Sailor]

Fyne Boat Kits do the Eastport Pram which is an attractive little dinghy. You can get plans or a precut kit.

 

[AntarcticPilot]

I built a dinghy - a D5 - from A4 plans. It wasn't particularly difficult to scale the dimensions up onto the plywood; the plans gave key dimensions. I did find an error in the plans!

Always worth remembering that smooth curves are usually defined by a few key points, and plotting those out and joining the dots with a flexible length of batten will get a fair curve.

 

[colhel]

I built a dinghy - a D5 - from A4 plans. It wasn't particularly difficult to scale the dimensions up onto the plywood; the plans gave key dimensions. I did find an error in the plans!

Always worth remembering that smooth curves are usually defined by a few key points, and plotting those out and joining the dots with a flexible length of batten will get a fair curve.

Thanks. It was cutting the curves, that seemed to me, full-size would be plans would be most useful. So, the dots are measured from a base line and side line and then joined up?

 

[AntarcticPilot]

Thanks. It was cutting the curves, that seemed to me, full-size would be plans would be most useful. So, the dots are measured from a base line and side line and then joined up?

Basically, yes. Use a long, flexible batten to join the dots - clamps and weights will hold it in place while you draw the curve. While we tend to think of splines as being mathematical curves, the term in fact derives from the use of splines (flexible battens) to delineate curves!

 

[colhel]

Yep understand. One of my jobs turning and milling and radii are one of the most difficult things to calculate and set up and my apprehension was borne from this, (though I hope the tolerances are a bit bigger on a dinghy ).

 

[Hacker]

You can use A4 if you can loft from the plans. You will need a full size lofting area (either a white painted floor or white painted wood - cheap ply or osb). You will then need to draw out some form of grid (usually waterlines etc) and then plot the points. Use nails in each point then use a flexible fairing battery to create the fair curves. With full size plans you can trace or prick through the paper.

 

[alahol2]

Here are the D5 plans... D5 Pram
I built a 1/10 scale model in card to see if it was possible to make it nesting. The model nests beatifully, all I've got to do now is build it.
As Antarctic P says, there is (was?) an error. I think it was something to do with the angle of the side plank and the transom bow.

 

[William_H]

I have built 2x Sabot 8 ft dinghies out of ply wood. Plans here sabot dinghy plans - Google Search

They row really well if you don't set up as a sailing dinghy. You make the transoms front and back then fit chines and gunwhales. A bit difficult getting the bend in these parts. You then attach the plywood and glue to hold it all together. The first one I built with 3/16 ply so quite light. I could lift it up on to catamaran fore deck and launch it off again so quite light. ol'will

 

[colhel]

Here are the D5 plans... D5 Pram
I built a 1/10 scale model in card to see if it was possible to make it nesting. The model nests beatifully, all I've got to do now is build it.
As Antarctic P says, there is (was?) an error. I think it was something to do with the angle of the side plank and the transom bow.

I have built 2x Sabot 8 ft dinghies out of ply wood. Plans here sabot dinghy plans - Google Search

They row really well if you don't set up as a sailing dinghy. You make the transoms front and back then fit chines and gunwhales. A bit difficult getting the bend in these parts. You then attach the plywood and glue to hold it all together. The first one I built with 3/16 ply so quite light. I could lift it up on to catamaran fore deck and launch it off again so quite light. ol'will

Many thanks! I'll have a look at them on PC later, give me more of an idea of what's involved.