A Photo & Discussion Forum for Wharram Design Enthusiasts

New Long Windows For Stock Tiki26

My Tiki 26 stock design windows are badly crazed, leak and some have cracks so I intend to replace them during the current refit. I quite like the look of the GRP 26s/8m with the single long sleek window on each hull but I'm not sure if my method of replicating that is the right way or could be improved.

This is what I think I will do. Assume at this point all old windows are removed, frames cleaned/repaired and the area inside and out is ready for fitting and new window material cut. I'll use the previous method of black mastic for sealing with a 5mm gap as this has not failed.

Reuse existing holes
Drill new holes, similar spacing, along the non window region between the original window cutouts, top and bottom.
Paint the area between the original windows black (I'll be using tinted window material)
Fit the new single window ensuring the mastic edge line is continued across the "gap" full length.

I'm aware of the need to ensure the soon to be covered area of cabin side will need to be in top notch condition to avoid degradation.

Obviously this is not an exhaustive list of steps but I hope will help describe what I'm doing.

So, will this work? Is there a better way? Anyone done this before?

Thanks heaps.

Replies to This Discussion

Permalink Reply by Robert Hughes on November 6, 2022 at 12:49pm

My GRP T26 has windows much as you describe. The acrylic goes the full length in one piece, but there are two separate cut-outs in the GRP coachroof side. I think it's better than one long cut-out as the middle "pillar" provides better support for the cabin top.

I think your approach should work but, depending on how big the pillar is and the consistency of the mastic, you may need an extra fixing hole in the centre of the pillar to get even compression.

What type of mastic are you using?

Permalink Reply by NeilR on November 7, 2022 at 2:39am

Thanks Robert.

My pillar is quite substantial and I won't be touching that. I agree some sort of centre fastener(s) may be required and during a dry fit that should become apparent.

The mastic I have is Selleys brand D Mastic. Skin hardens when exposed to air but remains soft inside. Formulated for boat and vehicle windows. It can be painted after the skin has formed.

Permalink Reply by Robert Hughes on November 7, 2022 at 3:52am

Thanks Neil, I'll make a note of that mastic for next time mine need doing!

NeilR said:

Thanks Robert.

My pillar is quite substantial and I won't be touching that. I agree some sort of centre fastener(s) may be required and during a dry fit that should become apparent.

The mastic I have is Selleys brand D Mastic. Skin hardens when exposed to air but remains soft inside. Formulated for boat and vehicle windows. It can be painted after the skin has formed.

Permalink Reply by NeilR on February 10, 2026 at 7:07pm

I hate posts that have not been tied off/completed.

I have completed the install of the new long windows but it took a while for me to get to them due to other priorities/problems appearing on the boat. I'm very happy with the results. This is what I did...

I used 6mm tinted acrylic. Cut with jigsaw and router. Rounded off the outer sharp edges. Window is fixed with "skyscraper tape" made by 3M (and used for window attachment in skyscrapers). Boy, it really grabs! I finished the edges with sikaflex silicone adhesive (same as the Dow stuff).

I did not paint any black on the boat, preferring to paint the back of the acrylic instead. I think this was a good decision.

So, now the post is tied off and complete. I hope this inspires another tiki 26 owner.