window replacement and mushroom vents.

I could not easily remove the rivets holding the windows in place. I drilled out the heads and removed the frames and perspex in the usual way, but could not knock the rivets through. The reason was they were glassed in on the inside with the inner liner. I had to drill holes on the inside to allow the rivets to pass, and I will have to repair these holes when I have finished. The central pins of the rivets had not rusted at all. I also found that the perspex was 5 mm. My boat is a Moores boat no 350. I understand some boats have 6mm perspex. This is being replaced with polycarbonate as it is longer lasting and cuts easier with a jigsaw. Perspex gets hot and needs great care when cutting with a jigsaw or it will melt.

The two mushroom vents are cheap plastic and have cracked. I have not yet found replacements as they are for an 80mm hole. Most vents seem to be 100mm now. I may get stainless steel ones from Vetus.

Hi Malcolm,

Stationerystill wrote

The reason was they were glassed in on the inside with the inner liner.

The rivets on my Reedcraft boat (#267) were not glassed in on the inside. I don't recognise your reference to an "inner liner" as something standard.

As far as I know no SeaHawk has a liner of any kind - just a solid GRP from gel coat through to the chopped strand matting on the inside. As the the windows are fitted after any moulding work is completed, the rivets pass all the way through what is already there.

Perhaps this is a "feature" of the earliest Moore's "crossover" boats and they were experimenting with new build techniques in those early days?

I see I should edit the text on the report of my changed windows. I use what I believed at the time was the generic term "Perspex". I now recognise that the replacement material was "Polycarbonate" and should have used that where appropriate.

Incidentally, as a follow up to that report, during the major refurbishment I did when Imagination became Just 17, because of the problems I had had previously with a borrowed rivet gun, I opted to replace the rivets with stainless steel dome headed Torx bolts and am very pleased with the results. The only issue was picking the best length for the bolts. The thickness of the GRP around the window edges varies significantly, with the result that some bolts protrude into the cabin more than I would like. Four years later and I am still to take an angle grinder I bought for the purpose to the bolts to cut them down to size.

Hi, just a note to add for any future window removers about my experience of this problem.

I have just had the same problem with my rivets in that, after removing the rivet heads and the windows I was left with the rivet body firmly stuck in place.
Trying to Drill this rivet body out just makes a mess of the hole, or leaves you with holes not aligned properly with the frame, and a rivet body still in place as the drill slips into the softer fibreglass rather than go through the rivet body.

As a man with 50 years of experience with a hammer and drift I surmised that they would not budge with "gentle tapping" so reached for a craftspersons next best friend the electric grinder to grind away any excess left on the outside or inside, and hey presto as soon as the heat from the grinding operation warms the bonding substance around the rivet body it will tap out very easily,you have to do one at a time ideally as they cool down and get stuck again very quickly.

Important point make sure that you catch the rivet body as it will be quite hot and could damage whatever it lands on and be very careful with the grinder fibreglass is soft and will grind very easily a dremel might work better than a full sized grinder if you have one.

This whole operation probably depend on what was used around the rivets as a bond and I suspect my windows were the original ones.

Good luck.

I believe mine were glassed over to prevent leaks. When I replaced the windows I also glassed over the rivets on the inside for the same reason.I used to build boats and have seen many window leaks but not on my Seahawk. I will not have the problem of removing them in future as the old ones were 40 years old and polycarbonate lasts longer than perspex.

I must have been incredibly lucky with my window replacement efforts!

I've removed the pop-rivets from around my windows twice in my 12 years with Just 17. The first time was when I fitted grey-tinted polycarbonate to replace the perspex windows that were there when I bought the boat. They had a dark grey film on them that was lifting off but did extend over the whole perspex surface, so I do not believe were original. The second time was when I opted to paint the frames black to better tone with the replacement polycarbonate I had fitted five years earlier.

On both occasions, after drilling out the heads, the remains of the rivet were easy to tap through the cabin sides into the cabin. As can be seen from the photographs on the Window Replacement page, I didn't even do the tapping while the rivets were still warm from the drill. I removed the heads from all rivets first, took photographs and then tapped them all out.

I have never seen any leaks in my windows, even before the replacement of the previous perspex. It occurs to me now that may be because the previous owner used the same sealant that I was advised to use by a local boat window specialist. It has a very particular rubbery texture when dry that granulates when rubbed.

I was relieved to find that after five years in place the polycarbonate stayed in place when I removed the frames in spite of the curve in the windows. I was half expected them to straighten out and break the seal.

I suspect that if previous owners have used the wrong kind of sealant, this will be why others report  problems tapping out old rivets. Certainly, bathroom-style silicone sealants have a tensile strength that the sealant I used lack and should definitely be avoided.

Given my experience, I firmly believe that glassing over the rivets should be unnecessary and just creates problems for subsequent owners.