Upside down, or rightside up?

[jsimpson]

I have had this system used on aluminum boats up to 50' in length . It usually starts with an inverted hull on a jig (including the deck) and when the serious welding starts, the boat is set up in what is essentially a 'skewer/rotisserie' arrangement to complete the welding without too much distortion. The one thing that must be watched is the center of gravity and good control must be maintained at each attitude of the hull. If the boat 'capsizes' in the shop a lot of damage and injuries can occur. It is also a rather noisy event. I think I may have some pics of a 50' RHIB -I will try to find and post if anyone is interested.
This rotation system is not new... the fiberglass builders have been using it for 30+ years.

[stuart hearn]

One interesting method i once saw was both upside down and right way up, the guy was a former tank designer who worked on the assembly of the tank hulls, he designed a large rotary jig, this consisted of two large steel wheels of about 7M diameter rolled from channel. These were located on substantial metal frames bolted to the floor, the framing was built inside them, it allowed the entire hull to be rotated into any position for plating and welding, and ran on a series of rollers hydraulicly driven via the tensioning wheels. This was simply drilled when in the correct position, and large numbers of 20mm high tensile bolts inserted.

This method was somewhat unorthodox, but very effective as he was not too good a welder himself, so preferred downhand welding, this method was limited to around 40' length, but the rotary wheels were designed for a 60 tonne tank so weight was not an issue. Wish i had my camera with me now as his method was ingenious.

yes quite, but the French have been doing that way for 50 years,

[nukisen]

Stu!

I think the easiest way to start is to level some pots and place the deck upsidedown. This makes it very easy to make a plan deck Also the mounting of profiles Is very easy to maintain on the deck. After you have assemble the bulkheads then it is quite easy to follow with the frames. When assembly the most of details you do all the easy welding downhanded. Also the outsid of shell is quite simple to weld. When you think the construction is stiff enough you are able to turn the hull around for welding downhanded again. Also a stand set for the hull I assume you have to build anyway as the boat not only planned to be in water.

Abut the turn around in mind regarding to drawings is solving itself very soon.

My opinion is this is easiest. Of course there will be som vertical weldings. But you don´t have to weld upside down strings.

//Janne