Is an RDM Extendo a bad idea?

Hi everyone,

After breaking my 370 SDM I have made my move over to RDM.
I have an RDM only severne enigma that's been sitting around and I can finally use it.

My NP 3.7/4.2/4.7 combats all rig on the 370 RDM.
My 5.7 Firefly, however, has a luff of 440.
I have an SDM 430 but it means lugging around and using a different (and crap) boom for the SDM mast.

I have read about SDM Extendos made from bottom sections of masts. Powerex also made these.

Has anyone made one from an RDM mast? I would like to rig all sails mentioned above on my 370.

Any problems I should know about?
I have read masts tend to be reinforced where the boom clamp goes, which is a problem if you start clamping your boom elsewhere.

Thanks in advance for the advice!

He wants to go RDM and use his Enigma is a boom. The smaller Enigma booms are made to suit RDM masts. He is not talking about an Enigma mast. He probably has masts to suit the sails he owns but his longer masts are SDM and the Enigma boom doesn't fit SDM and is looking for a solution to be able to use an RDM boom on a SDM mast or a mast extension that will allow him to use a 370 for sails that recommend a 400 or 430.

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KA360 said..
He wants to go RDM and use his Enigma is a boom. The smaller Enigma booms are made to suit RDM masts. He is not talking about an Enigma mast. He probably has masts to suit the sails he owns but his longer masts are SDM and the Enigma boom doesn't fit SDM and is looking for a solution to be able to use an RDM boom on a SDM mast or a mast extension that will allow him to use a 370 for sails that recommend a 400 or 430.

Yes, thanks I should have read the OP more carefully.

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John340 said..
I have no experience with a RDM extendo.

However I'm not sure an Enigma RDM mast will work efficiently with your NP sails? The Enigma mast is at a hard top compared to the flex top NP sails. They will rig but they will not have the optimum shape.

Check out the Unifibre mast selector comparative tool

unifiber.net/unifiber-masts-selector-2019-v1

Sorry I realise that it wasn't clear in my post. As others have mentioned, it is indeed a skinny Enigma boom and not a mast. I have purchased a flextop 370 Unifibre C80 for my NP sails.

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Mark _australia said..
A Firefly is a magnificent sail so I can see why you want to use it, but no way will you get it on a 370.

Extenders should be minimal for the boom area as you mentioned but also as the curve and stiffness changes. 10-20cm extender with some loss of performance. Maybe
70cm!!!???? OMG no

At the moment, my Firefly is almost in 2 pieces. so am weighing up whether to get it repaired or find a replacement sail.
Sounds like rigging a 5.5m ish sail on a 370 won't be possible in that case. Even a 2022 5.3 combat has a 420 luff (so would need something like 30cm extendo and 20cm extension).

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gorgesailor said..

This is a bad idea & strength is the least of your worries. Even using 40cm RDM extension on a 400 mast is not a good idea. Flextop sails tend to be pickier about bend curve than CC or even hardtop sails. The NP will definitely want a flextop mast. I would find a used 430 NP RDM mast or even look at other Flextop leaning masts like Hotsails, Simmer, Goya ..etc or buy an aftermarket mast like a Chinook which is CC leaning to Flextop or something like a Unifiber which has different bend options.

You have a nice sail, a nice boom, don't skimp on the mast you will regret it.

Thanks for the advice. I've got a 370 c80 flextop unifibre for the other sails.
I think it may just be easier to keep using my 430 SDM mast and the crappy boom for the time being rather than getting an extra mast just for 1 sail. I also use the X9 430 SDM with my 6.7 freerace sail but use yet another boom for this sail!... This sail is definitely better off on SDM as I'm using it for "slalom".

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Aus501 Boz said..

gbm91 said..

John340 said..
I have no experience with a RDM extendo.

However I'm not sure an Enigma RDM mast will work efficiently with your NP sails? The Enigma mast is at a hard top compared to the flex top NP sails. They will rig but they will not have the optimum shape.

Check out the Unifibre mast selector comparative tool

unifiber.net/unifiber-masts-selector-2019-v1

Sorry I realise that it wasn't clear in my post. As others have mentioned, it is indeed a skinny Enigma boom and not a mast. I have purchased a flextop 370 Unifibre C80 for my NP sails.

Mark _australia said..
A Firefly is a magnificent sail so I can see why you want to use it, but no way will you get it on a 370.

Extenders should be minimal for the boom area as you mentioned but also as the curve and stiffness changes. 10-20cm extender with some loss of performance. Maybe
70cm!!!???? OMG no

At the moment, my Firefly is almost in 2 pieces. so am weighing up whether to get it repaired or find a replacement sail.
Sounds like rigging a 5.5m ish sail on a 370 won't be possible in that case. Even a 2022 5.3 combat has a 420 luff (so would need something like 30cm extendo and 20cm extension).

gorgesailor said..

This is a bad idea & strength is the least of your worries. Even using 40cm RDM extension on a 400 mast is not a good idea. Flextop sails tend to be pickier about bend curve than CC or even hardtop sails. The NP will definitely want a flextop mast. I would find a used 430 NP RDM mast or even look at other Flextop leaning masts like Hotsails, Simmer, Goya ..etc or buy an aftermarket mast like a Chinook which is CC leaning to Flextop or something like a Unifiber which has different bend options.

You have a nice sail, a nice boom, don't skimp on the mast you will regret it.

Thanks for the advice. I've got a 370 c80 flextop unifibre for the other sails.
I think it may just be easier to keep using my 430 SDM mast and the crappy boom for the time being rather than getting an extra mast just for 1 sail. I also use the X9 430 SDM with my 6.7 freerace sail but use yet another boom for this sail!... This sail is definitely better off on SDM as I'm using it for "slalom".

Not sure if it's the same but I run a Enigma carbon free ride boom on both my RDM and SDM masts, the cup that secures the boom to the mast is SDM but there is enough flex in the holding mechanism to secure the rdm by just changing the rope length. Speak to Paul from revolution board sport he might be able to verify if you can do this to a wave boom.

I did try my skinny Enigma boom on the SDM mast at the beach once, but some of the more experienced sailors gasped in horror when I did.

Definitely enough flex for the outside of the cup. Although there is some point loading on the mast as the diameter of the centre of the cup is too small and it is rigid.

Select to expand quote

Aus501 Boz said..

gbm91 said..

Aus501 Boz said..

gbm91 said..

John340 said..
I have no experience with a RDM extendo.

However I'm not sure an Enigma RDM mast will work efficiently with your NP sails? The Enigma mast is at a hard top compared to the flex top NP sails. They will rig but they will not have the optimum shape.

Check out the Unifibre mast selector comparative tool

unifiber.net/unifiber-masts-selector-2019-v1

Sorry I realise that it wasn't clear in my post. As others have mentioned, it is indeed a skinny Enigma boom and not a mast. I have purchased a flextop 370 Unifibre C80 for my NP sails.

Mark _australia said..
A Firefly is a magnificent sail so I can see why you want to use it, but no way will you get it on a 370.

Extenders should be minimal for the boom area as you mentioned but also as the curve and stiffness changes. 10-20cm extender with some loss of performance. Maybe
70cm!!!???? OMG no

At the moment, my Firefly is almost in 2 pieces. so am weighing up whether to get it repaired or find a replacement sail.
Sounds like rigging a 5.5m ish sail on a 370 won't be possible in that case. Even a 2022 5.3 combat has a 420 luff (so would need something like 30cm extendo and 20cm extension).

gorgesailor said..

This is a bad idea & strength is the least of your worries. Even using 40cm RDM extension on a 400 mast is not a good idea. Flextop sails tend to be pickier about bend curve than CC or even hardtop sails. The NP will definitely want a flextop mast. I would find a used 430 NP RDM mast or even look at other Flextop leaning masts like Hotsails, Simmer, Goya ..etc or buy an aftermarket mast like a Chinook which is CC leaning to Flextop or something like a Unifiber which has different bend options.

You have a nice sail, a nice boom, don't skimp on the mast you will regret it.

Thanks for the advice. I've got a 370 c80 flextop unifibre for the other sails.
I think it may just be easier to keep using my 430 SDM mast and the crappy boom for the time being rather than getting an extra mast just for 1 sail. I also use the X9 430 SDM with my 6.7 freerace sail but use yet another boom for this sail!... This sail is definitely better off on SDM as I'm using it for "slalom".

Not sure if it's the same but I run a Enigma carbon free ride boom on both my RDM and SDM masts, the cup that secures the boom to the mast is SDM but there is enough flex in the holding mechanism to secure the rdm by just changing the rope length. Speak to Paul from revolution board sport he might be able to verify if you can do this to a wave boom.

I did try my skinny Enigma boom on the SDM mast at the beach once, but some of the more experienced sailors gasped in horror when I did.

Definitely enough flex for the outside of the cup. Although there is some point loading on the mast as the diameter of the centre of the cup is too small and it is rigid.

Might have misread what you have but isn't your cup for the RDM? With my boom the cup is for an SDM mast so when you put an RDM on it fits snuggly to the bottom of the cup by just tightening the rope there is enough flex for the outside to hold it securely in place even though the Cup is for an SDM. For the SDM mast it fits snuggly as intended.

The boom cup appears to be RDM only.
There is also no removable sleeve for SDM to RDM.

Last time I tried it, I recall the SDM mast not fitting well at all. Will try to get some photos this week

I switch between RDM and SDM with a skinny tube Enigma boom without any problems.