Thread: Need a Dinghy/yacht tender

6'x3' 6" is 21 square feet, which is more then enough to support you and some gear. Assuming a pram style of hull, vertical side, maybe 15" to 18" of freeboard, you can expect it to carry a fairly hefty load, with just a few inches of immersion. For example, if you sank this shape down with gear, say you, a well fed friend, Fedel the wonder dog and a cooler full of beer, causing her to trim out with 6" of boat below the water, you're holding in the general vicinity of 600 - 650 pounds (38 stone). If the boat has 15" of freeboard, you still have 11" left.

Thanks PAR,

Had a bit of fun this afternoon.

I made a quarter scale model of what I think would be called a pram dinghy.

loa .45
beam .25
overall depth .16

out of chipboard & cardboard.

Lined it with a bin liner and filled it with water / +/- 10 litres

Using the above dimensions assuming totally box shape the volume would be 18 litres

At 10 litres it will sink at 10Kg load in fresh water.

As it is quarter scale in every direction actual dinghy will be 64 x the volume.

Actual dinghy will sink at 640 Kg

I then coated the outside with clingfilm, popped her in the bath and added a 1.25 Kg bag of sugar to represent me and she floated in 50mm

another 1.25 Kg took 70mm to float her in

finally with 3.75 kg sugar 82mm

this equates to the dinghy as follows

80kg draught 200mm
160kg 280mm
240 328

leaving freeboard as follows

80 430mm
160 355mm
240 305mm

I suppose I should do some inclination tests but the results would not mean much to me but she did seem stiff.

Does this make any sence?

Mike

Hi, Mike,
Ever thought of a Seahopper?
It's an 8' long pram which folds flat & stores in a bag.
I had one a few years ago.
It was b..... useless on open water, but it should be fine for what youre wanting.
It's very easy to throw on the roof of a vehicle & doesn't need much room to store.
They may be still available new, or there might be second hand ones around.
Just a thought.
Bill.

Thanks Bill,

I have now built a dinghy out of WBP ply from a builders merchant. I ended up using a plan for a Portugese high bow dinghy from Hannu's site. He gave dimensions for a 5' 6" and 7' 6" dinghy. I modified the plans and have made a 6' 6" dinghy and made it a few inches less in the beam. This is a nice fit in the back of my Land Rover. I also made it of 9mm ply. Frightened to put my fingers through 6mm while handling it!

Found the dinghy very easy to build. Purchased fibreglass kit, rowlocks & whatever I needed off ebay. Total cost about £80. Just needs a few coats of paint now.

I have had to make this dinghy in a rush to be able to get to my new mooring. Next winter I will probably make another and may opt for marine ply. I have learned a few things during construction. In particular once the sides & transom are connected they are placed on a fresh sheet of ply to be scribed round for the bottom. I cut the bottom out from the edge of the sheet but later realised I should have cut the bottom from the centre of the sheet then the waste could be fastened to the top of the dinghy in a complete piece to make side decks which is one way of stiffening the structure.

I feared building in 9mm ply might make a dinghy too heavy for an old codger (like myself) to carry around but this is not the case.

Mike

I have also made a pair of oars, 2m long. Can shorten if too long.

I have realised as the craft is only 40" beam I might be better to fit the rowlock seats (not yet fitted) outboard of the gunwales. This has the effect of providing another 4" or so of beam and be better to row. With very narrow beams I imagine you have to make lots of short strokes?

Mike