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expanding foam injected into a mast
http://www.hobie.com/au/en/forums/viewtopic.php?f=14&t=10635		 Page 1 of 1
Author:  shawnkillam [ Fri Sep 05, 2008 7:57 am ]
Post subject:  expanding foam injected into a mast
Has anyone injected expanding foam into a mass to deal with leaks. My (new to me) boat has significant leaks under the forestay tang. The old type was replaced with the three hole variety but not properly sealed. I am reluctant to drill it out / seal and replace but it may come to that. I can inject the foam through the holes left from the old tang.

My concern is that the force from the expanding foam could damage the mast. I think the chances are small but I do not want to find out the hard way that I was wrong. I have seen this stuff lift a screwed down piece of sheet rock off a wall.

All thoughts gratefully appreciated.

thx sk
Author:  The Dog [ Fri Sep 05, 2008 11:00 am ]
Post subject: 
http://greatstuff.dow.com/greatstuff/diy/products/wd.htm

Image
Author:  aschaffter [ Fri Sep 05, 2008 3:17 pm ]
Post subject: 
Keep the mast out of the water! :D :D

Are you going to inject the stuff in a bolt hole? or remove the comptip and replace the existing plug (or is the plug at the top of the comptip or both?- I forget).

Anyway it is best if you do it with the mast standing upright or upside down so the foam doesn't spread out along the length of mast. You want a plug and not a foam-filled mast.

Also, expanding polyurethane foam is activated by moisture. When sealing gaps around a house it uses ambient moisture. If the inside of your mast is dry, you may need to sprits a little water in the hole first.
Author:  flocktothewall [ Fri Sep 05, 2008 3:24 pm ]
Post subject: 
Quote:
t is best if you do it with the mast standing upright or upside down so the foam doesn't spread out along the length of mast.


Definitely try to get the mast upright with some sort of a plug. Otherwise you have some 26' of potential foam, and to fill the mast with too much will add extra weight aloft, which isn't a good thing. When I replaced my '74 tang with a new 3 hole style and comptip, I used the plug supplied with the comptip to create a plug, and then filled the rest the the same stuff, it worked great, took longer to dry than I expected for some reason. You could also just try to put rivets and rivet seals in the unused holes. Instead of trying to foam up the mast.

Luke
Author:  shawnkillam [ Fri Sep 05, 2008 3:50 pm ]
Post subject: 
Thanks for the input.

The new three hole tang was placed partially over the old holes. The ones that are visable are not a problem it is the couple that are hidden up under the new tang that I cannot get at that are causing me grief. I drained about a half gallon of water out before I started this so hopefully there is enough moisture in there to set off the foam. I have gone ahead and tried it, as the consensus seems to be that it won't do any harm. I set the mast upside down and mostly verticle and we shall see.

As a "by the by" I am pressuriing the hulls, mast etc to test for leaks by using a simple latex balloon. I blow it up with a compressor and have all kinds of couplings, valves, t fittings etc but that is just me - after all any job that doesn't require getting a new tool isn't worth doing. Others who have a better grip on reality than I do could just blow it up manually. It provides enough air pressure to test for leaks and not enough to damage anything.

sk
Author:  shawnkillam [ Fri Sep 05, 2008 4:13 pm ]
Post subject:  confessions of a ludite
I am about to admit ignorance - not something I do well but - what is a comp tip and what does it do. I went to the catalogue which wasn't much help and the forums that discuss installation but all I can figure out is that it seems to be a mast extension. Is this correct? If it is what benefits are achieved and if it isn't what is it?

thanks sk
Author:  flocktothewall [ Fri Sep 05, 2008 5:08 pm ]
Post subject: 
Its an add-on for later boats, I think its standard now. Basically its a third or so of the mast made out of carbon fibre instead of aluminum. It is safer around power lines (apparantly it was a big problem back in the day) and it also provides better control in light winds. If you want to race you need one to be "legal."

Luke
Author:  aschaffter [ Fri Sep 05, 2008 8:01 pm ]
Post subject: 
Info is in the FAQ
Author:  shawnkillam [ Sun Sep 07, 2008 9:58 am ]
Post subject: 
Thanks all for the info.

Out of curiosity does anyone have any statistics on the number of masts contacting power lines and the subsequent problems?

thx SK
Author:  aschaffter [ Sun Sep 07, 2008 10:13 am ]
Post subject: 
flocktothewall wrote:
Its an add-on for later boats, I think its standard now. Basically its a third or so of the mast made out of carbon fibre instead of aluminum. It is safer around power lines (apparantly it was a big problem back in the day) and it also provides better control in light winds. If you want to race you need one to be "legal."

Luke


Fiberglass with blackening to reduce UV damage, but definitely not carbon which is also conductive!
Author:  sunvista [ Tue Sep 09, 2008 5:36 am ]
Post subject: 
shawnkillam wrote:
Thanks all for the info.

Out of curiosity does anyone have any statistics on the number of masts contacting power lines and the subsequent problems?

thx SK
Yeah... most only ever did it once. :shock:
Author:  shawnkillam [ Thu Sep 11, 2008 2:35 pm ]
Post subject: 
Quote:
Yeah... most only ever did it once


The implication is that there were no subsequent problems. I have heard that electroshock is a great treatment for depression. Is there any indications that such individuals were in a better mood after encountering the power lines? Enquiring minds want to know.
Author:  Sail Revolution [ Thu Sep 11, 2008 4:27 pm ]
Post subject: 
I put some expansion foam in my first Hobie 18 back in the early 90's. Eventually it became so heavy I could hardly raise the mast. I weighed the mast and it was 84#'s I would advise against putting anything inside the mast. It took days to dig it out.
Seal up the mast, then get a bob if you need more float.

I guarantee if you sail your boat with foam in the mast for a few years you WILL need electroshock. :wink:
Author:  The Dog [ Thu Sep 11, 2008 6:51 pm ]
Post subject: 
Jeremy, ya goof.... You weren't supposed to fill the mast with foam! Just a dollop at each end. :lol:
Author:  Sail Revolution [ Thu Sep 11, 2008 9:19 pm ]
Post subject: 
Yep, learned that the hard way!
J
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