I'm shopping around for an rdm mast extension to fit my sail quiver. Planning to buy alloy as I've heard that carbon extensions are more prone to failure and I've noticed that long rdm extensions of 40-45cm are readily available.

Any opinions on the longest practical (and safe) extension length for an alloy rdm mast extension when used with a 430 mast?

Also, has anyone had any failures when using a long rdm alloy extension?

I've seen all types fail, though the least amount of breakages i have seen are from carbon. I had a 40cm ring and collar alloy extension (quite a heavy unit, though I have seen 1 fail) that worked fine though i never landed it from big jumps etc it was only used with a race sail and only at about 35cm extension.

Food for thought though- consider the wall thickness of a mast and the area it can spread the load across. Then look at your extension, certainly no carbon extension comes close to wall thickness of masts and alloy is hit and miss. IMO if you need over a 25cm extension for an rdm start looking at an extender.

I've got 2 RDM 45cm alloys, one bent a bit, but otherwise going well

No issues, using on a 400 and 460

Got mine from Windsurfingsales and one of the ws shops in caloundra - think city sailboards - the basic thick alloy, no brand job

These are pretty meaty, I reckon ya mast would break before one of them did (the might bend at worse)

I've got 2 Pro-limit Rdm extensions, 1 carbon and 1 alloy both 45cm. I always go for the carbon one first and just have the other one handy if i need to rig a second sail. I use a 430 rdm pryde X6 and set the extension to 34cm for a 6.7, As with anything they will fail at some point and that's just part of life....whats the point of making a extension that goes to 45cm if you can't actually set it to 45cm and use it as intended by the manufacturer.....Just hope it snaps or bends while under warranty.

I have destroyed 2 1/2 alloy rdm extentions, without any mast failures.
Basically my conclusion is that setting an extention at 40cm is too long for wavesailing in rough places like Scarborough.

Its just I am too cheap to buy a longer mast so am persisting with the long RDMs.
They were good brands as well. 2 Techno Limits and now I have a slight kink starting in a Aeron. I would love to test a carbon to do the job but can't afford a $220+ experiment.

Select to expand quote

mkseven said...

IMO if you need over a 25cm extension for an rdm start looking at an extender.

Checked out the Powerex 'Extendo' on their website which are available in 40cm and 60cm lengths, so won't really be suitable unless the luff is above 470cm when using a 430 mast.

I'm in the process of changing from sdm to rdm hence my reason for shopping around for a new extension as well as asking these silly questions! My future plan is to purchase a 6.6 with 462 luff as my biggest sail so would only need maximum of 32cm extension with 430 rd mast. Bit surprised that carbon rdm extensions have had far less failures for some as I heard from 'reliable' sources that they were weaker than alloy rdm extensions!

What about brand reliability, are Chinook the benchmark for strength?

Select to expand quote

GazMan said...

mkseven said...

IMO if you need over a 25cm extension for an rdm start looking at an extender.

What about brand reliability, are Chinook the benchmark for strength?

Broke 28cm chinook rdm alloy extension on first time use when selected 26cm hole.
Was a " BIG BOMB" of a wave and i got worked.
Mast was powerex 430 no damage. Went straight out and bought another Chinook same ext. 6mths of use now and still goin no probs.