This was quick and safe process and I think it deserves to be posted.
After a pathetic and cold washing at Montrose yesterday I've got a stuck mast for a dessert on top of everything. This mast is fairly new, used only a dozen times maybe and very tight fitting and even though Ive taped it beforehand it got stuck so badly that not 2, not 3 and not even 4 men, 2 booms and no amount of banging, bending, water and lubricant spraying were able to separate it. This has happened twice before, but both times it took only one more person to be able to unstick it on the spot. This time though it was like welded together! After 2 hours of epic struggle I accepted the defeat and took it home like that-protruding out of my cars front passenger window. Some more banging and screwdriver prying later in the garage did nothing but some damage around the edges .
The resque idea came to me today while at work and during a break I went home , heated a kettle of water to a boiling point, attached 2 booms with additional rubber "gaskets" made out of bicycle inner tube close to each half of the mast and started pouring the hot water slowly over the space where the ferule was supposed to be .
Typically for me -blame the ADD- I poured over the wrong half of the mast so it took me 2 tries and a torn apart boom clamp rope until the halves finally started pulling away giving me a hard time to the last inch!
So this is how you separte a stuck mast by yourself without damaging it:
-attach 2 booms really tight to each half of the mast and close to the connection, use some rubber-like inner tube- for more friction
-heat the connection somehow -probably hot water is the easiest and safest way
-start twisting the booms in opposite directions
-repeat if needed and in extreme situation you may also try to chill with ice the male half, while heating the female simultaneously / shrinking the inside and expanding the outside -does this make sense?/
After the separation I've sanded down the ferule a fair bit after a tip given by Andrew a while ago so I hope the looser fit and taping should spare me any more troubles.
I hope this short guide to be able to help somebody else in a similar situation !
Many thanks to everybody who tried to help me at Montrose! I really appreciate it guys!!!

The Rubber Mallet Approach:

IF, all else fails the following may just do the trick. Three Men, Two booms, One Rubber Mallet and some water: Attach the booms as described above. Have the two Men apply counter torque to the mast joint. While the joint is under torque, have the third Man hold the mast in one hand and begin 'thumping' the mast joint over the inserted ferrule section. The "thumping" should be applied around the mast, not just in one sector. The thumping must be performed with respect for the mast at all times. Constantly pour water (warm, soapy water will penetrate the joint better than cold water) to the mast joint to increase lubricity to the joint. Rhythmic chanting and/or grunting will aid synchronization of all applied forces to the mast.......

Notes: The term "thumping" used here can be related to the word "thwacking" (which is a softer form of banging). In "no-way" am I suggesting banging or, beating the mast with anything hard. A "Rubber" mallet is not, a steel hammer nor, a piece of wood. It is designed to deform a bit under impact.

Nice hack Ady! that was a great sesh at montrose that day, too bad the mast problem ended your day with frustration, im sure. Next time, double tape the mast!!
I never thought of the heated water technique, will need to try it next time (although the tape has eliminated any stuck masts for me for couple years now). At least you got yours seperated, andrew ruined his mast trying to separate...

alan schmid wrote: Yeah, the hot water and the rubber "gaskets" out of bike tire inner tube which made the booms hold tighter-I was lucky I've had them in a box in my garage /I'm a bit of a hoarder according to my wife / Ill keep those rubber pices in my tool bag from now on .

inner tubes....gotta love them! I wore through the soles of my expensive booties a few months ago, inner tube rubber repair ensued. Shoe goo was the adhesive I used.
These are 7mm dry lock purchased last summer, and they wore out quick. it is the non-skid surface of our boards that wear it out quickly.

Douglas King wrote: I tried a rubber mallet banging too-to no avail. Kudos to Nolimitz-those Sumo masts are extremely tough at the expense of some added weight though.

My preventive measure is the use of red electrical tape around the joint. The tape not only helps keep silt and sand out of the joint but helps keep the joint together when removing the mast from the mast sleeve (luff). Tape is simple and effective.

The mallet approach is the last hoorah. And, it does indeed work when assisted with clamp-on booms top and bottom. This is straight forward for me since always carry a spare boom. And if alone, the one boom can usually be wedged against or under something while the other booms man-handled.

A note is in order here regarding some of the newer masts which are no longer supplied with internal plugs. For the base half of the mast this allows the top half of the mast to be stored inside the bottom half. This saves space but, also allows air out of the mast and water, silt and sand to enter when submerged. This not only adds weight to the mast when up-hauling or water starting but also, allows sand and silt (and water) into the length of the mast One of the best services at some windsurf shops is to install plugs in the masts.