Anyone Built a Nesting Aluminium Dinghy ?

[conachair]

I'm looking into it at the moment. Thought I'll start by drawing up something in 3D cad maybe based on a D4 (free plans!) Free boat plans from Bateau Need to 3d it to make sure it will fit behind the mast as well.
Then I should be able to get all the panels laser cut from the supplier. I have a friend who recently made an ali jet boat in NZ so he should know what grade of ali and what stiffening might be required etc.
I would be very interested in anyone else's experiences of any thoughts in general. Or are there better free plans out there already?
Only downsides i can see are weight and tricky to get back into after snorkling.

big TIA

[capngeo]

Just curious..... but why?

[conachair]

Originally Posted by capngeo

Just curious..... but why?

Many reasons, inflatable tinker tramp is at deaths door so need something or other, have got access to a fabrication workshop so should be cheaper than buying new, will last forever when I get back to full time cruising in the sun and getting dragged up beaches, less likely to get nicked, should be able to design it to fit in available space, cos it might be fun With a sail as well hopefully. Maybe.

[capngeo]

I've come full circle on dinks... Started years ago with inflatable roll-ups, then RIB, then got tired of patching and went to Boston Whaler types; 8', 11', then a 13' with a 50 horse! (BTW THAT one was fun!). Due to weight, I had to tow all the time.

I've downsized to a Cal28... The 11 foot "dink" cost me 2 or 3 knots and was forever tugging the stern around or bumping into the sailboat while at anchor and waking everyone up..... I'm back to a roll-up!

How do you plan to launch/recover the aluminum boat? What sea-state do you think you'll be in most of the time? How about fendering? or floatation if swamped?

My background is in commercial vessels.... metal themselves, with big powered cranes on deck.. Metal tenders make a lot of sense there.. not on a cruising yacht (IMHO)

[conachair]

Originally Posted by capngeo

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How do you plan to launch/recover the aluminum boat? What sea-state do you think you'll be in most of the time? How about fendering? or floatation if swamped?

v early days in this, havent even calced the weight yet. launch will be halyard on a winch or windlass using spinakker pole as a jib, worked for the past few years with previous dinghy & outboard. Flotation will be built in, doubling as dry storage for shopping etc with watertight hatches. Sea state? How should I know? Sheltered anchorage I hope! Fendering? Dunno, can't be that hard, there are dinghys around and they all manage so thick rope?

[capngeo]

If you can get your hands on some fire hose jacket and closed cell neoprene pipe insulation.. it works great! Link to pix of my 11 with the fire hose fendering

[CFR]

joohee building nestor

have a look on thisa pram from e guy in eastern europe

[Matt Johnson]

I built this two years ago when I needed a winter project. Was it worth the time?... yes! Worth the cost?.... absolutely not! I spent over $1600 on wood, fiberglass, epoxy, sanding equipment and paint.

Should have bought a used RIB!





Here are the plans if you still want to do this foolish project.

spindrift

[conachair]

nice looking dinghy, but $1600 !!! I'm a bit catch 22 at the moment as I need to decide on a set of plans to get a quote on the ali but don't want to commit until i know more about weight and cost. Though 1085 grade seems well within the budget, £85 for a 1m x 2m sheet, though I have no idea how much more the cost is for 6082, which seems to be the favoured grade for marine use. Laser cutting would add a bit more but after that it's mostly labour. And I lose the free use of a workshop in a couple of months so maybe my cunning plan will come to nought.

Have you sailed yours? The 9' version looks like it would suit me well, will fit on deck folded.

[Matt Johnson]

Originally Posted by conachair

Have you sailed yours? The 9' version looks like it would suit me well, will fit on deck folded.

Nope... the plan was to make it a sailing dinghy, but somehow I lost interest after I added up the receipts! Also, I don't get out sailing enough on the big boat.

I'm sure you could do it for much less, but by using the correct materials (wood, epoxy and paint) the cost would be close. I may have spent $300 more than necessary on extra fiberglass and epoxy since I was new (lost a lot to waste), but I don't think I over build it.

[GordMay]

Originally Posted by conachair

... Though 1085 grade seems well within the budget, £85 for a 1m x 2m sheet, though I have no idea how much more the cost is for 6082, which seems to be the favoured grade for marine use ...

Both 5052 (Ductile for skins) or 6061 (Strong but more brittle for structure ) alloys are used for boats operating in saltwater environments.
There is some use of 1100 series (weak/soft but the best corrosion resistance) in non-structural (often decorative) applications.

The linked table gives main features of some marine grade aluminum alloys (series 5xxx and 6xxx; in blue font) and a few others for reference:

➥ Aluminum Alloys

[KestrelBuck]

Here is a link to my nesting dinghy project from some years ago. It was worth both the time and money.

New Page 1

We took this dink to the Bahamas in addition to our roll-up. The roll up went in the lazarette and the nesting dinghy fit between the mast and the traveler. At the time my son was 18 so he needed his own transportation in places like George Town.

[noelex 77]

The best material to use for an aluminium boat is:
5083 closely followed by
5086
5052 is considerably cheaper but is less strong.

The stringers etc need to be extruded and this is best done with one of the 6*** series of aluminium.

For your project the hull thickness is going to be much greater than needed for strength as aluminium thinner than 4mm is very difficult to weld.
For this reason the cheaper 5052 would be a sensible choice.
If you move away from the 5*** series aluminium (or 6*** for extrusions) you will get corrosion problems in seawater. Different grades of aluminium have very different resistance to seawater corrosion. There are horror tails of boats constructed out of totally unsuitable grades of aluminium.

The main problem I see with your project is weight. The dingy would ideally be constructed from much thinner aluminium than it is possible weld.
Commercially produced dingys are pressed rather than welded.

If you can live with the weight and cost of 4mm aluminum you will have a super strong durable dingy.