Much has been said and praised in this blog about Butyl tape.  Its practically Dani’s pet.  But we’ve only begun to put it to the test it seems.  After much discussion and hemming and hawing over what to try to rebed the portlights with, we decided to give our old standby another go and see if it can live up to the job.  The alternatives of course would have been either a polysulfide caulk or something like 3M 4200.

Who can say why we decided to go with the butyl.  We’ve seen many articles on bedding portlights with butyl tape but none of the port lights were quite like these old style things that Sundowner sports.  Its a spigot that passes through the cabin top and then a ring fits around the spigot on the exterior.  The ring isn’t a perfectly tight fit.  So as you can see the main places that will need to seal are the joint between the spigot and the cabin top and also the bolt holes.   I guess we just got a wild hair and wanted to try it.

Portlight with old caulk

We started the usual way.  You know, taking nuts off of long corroded screws.  Hammering them out.  Using paint scrapers to remove so many years of built up old caulk, rust, and junk.  We then sanded the area, used a scrub pad, then dusted and finally I wiped all the surfaces down with some Acetone which ate right through that dinky little rubber glove I’m wearing.
Tate cleaning the portlight in prep for butyl tape

This is what the parts looked like when they are cleaned up a bit.
Cleaned portlight ready for butyl tape

I had Dani do all the hard work.  You know, like digging the old caulk out of the grooves of the old screws.
Dani cleaning the bolt head for butyl tape

We then proceeded to mash a metric buttload (technical term) of butyl tape into the gap between the spigot and the cabin top.  This seemed to work well as the butyl adhered to both the metal and fiberglass so much so that even digging in it or pressing on it with a screw driver wouldn’t unseat it at all.  We also made little donuts around all the bolt holes.
Portlight with butyl tape used around

I carefully put a line of butyl around the underside of the flat head bolts and then drove them back through.
Tate hammering in bolts with butyl tape

And voila.  A portlight that looks almost exactly the same as it did when we started.

Finished portlight bedding with butyl tape

The real question though is… Will it leak?  Is the butyl compressed well enough by the trim ring to stay in place and not let water in?  Will the bolt heads keep proper seals against the metal?

Find out the answers to these mysteries and more… Next time on Sundowner Sails Again.