Extending The Length Of A Mould

[BB37]

I was wondering how longer boats are made from shorter boat mould. E.g. Richardsons 45ft mould/hull came first and then is was shrunk to the the 38ft version. As on their 45ft version the hull rises to the bow, and on the 38ft the bow is at the same height, so the angle/steepness of the hull is larger on the shorter version. 

[Vaughan]

It is done by literally sawing the mould tool in half, as Jonzo says.

Crown Blue Line made 4 boats out of 2 mould tools in this way. It is much more easily done on the bathtubs, of course.

It is also a good way of making best use of an expensive mould tool. Ben Mackintosh of Aquafibre once told me that they had to get at least 17 boats out of a mould tool before they could make a profit.

[grendel]

I suppose you could have a 3 part mould, front middle and back, then with just a different middle you could produce a different length. cheaper than building a new front and a new back.

[Viking23]

You also have the superstructure too, you can't have centre cockpits that are small medium and large lol.

I guess things were easier when built in wood.

With steel narrow boats, between the front and stern the section is of the same profile, in fact companies offer extensions, where they cut a boat in half and weld in a section, like a stretched limousine. 

[Regulo]

"Extending the length of a mould" - easy, leave the bread out longer.

[Oddfellow]

On 25/11/2016 at 10:43 AM, Viking23 said:

You also have the superstructure too, you can't have centre cockpits that are small medium and large lol.

I guess things were easier when built in wood.

With steel narrow boats, between the front and stern the section is of the same profile, in fact companies offer extensions, where they cut a boat in half and weld in a section, like a stretched limousine. 

The Aston Bournes were built exactly like this! Or at least if you look at one, you can imagine that's how they were built.

Rambliing Freedom appears to be sectional and quite possibly put together in a number of pieces rather than from one mould tool (whether bolted together or not). There are definite "joins" between the front superstructure, cockpit and rear superstructure. 

 

[webntweb]

Didn't Powles use the same mould in the late 70s for their 36 and 39 ft centre cockpits?

Don't know if it was the same one for the 42 footers though.