A24 Window replacement

This post was copied  from the old web site (reformatted and split into two parts), it describes the steps taken by Geoff Marks dropping and refitting the keel on "Zethar" in 2004. It is for illustrative purposes only, professional advice was taken before starting and during the job and you should do the same.

The line of the old sealant shows how close the Perspex was to the bottom edge of the midship and aft window holes. The gel coat had been lifted by the self tapping screws at most of the screw holes and they were all filled before new holes were drilled. 

To fasten the new windows an alternative to self tappers was needed and brass press-in inserts for 4mm machine screws were used. The inserts were too long for the grp and had to have 3mm taken off.

The inserts are designed to compress as they are pressed into a slightly undersized hole and then expand as the screw goes in so that the knurled surface of the insert grips the walls of the hole. This together with the flange on the inside stops them from pulling through the grp when tightened to give a very strong and secure fixing.

By taping the pre-drilled perspex in place it was able to be used as a guide for careful drilling through the grp thus leaving very neat lines of holes so that the new screws and inserts would line up accurately.

Each 4mm hole in the grp was drilled out to 5.5mm to fit the inserts and below you can see them in place.

The new window was attached with a single screw at each end but the next screws would not go in as the inserts were slightly misaligned. With the aid of a bradawl in the inserts to help alignment the screws were soon in place. The finish inside was very tidy with the 12mm long screws flush with the inserts.

After a successful dry fit the windows were bedded

Geoff Marks