Refitting windows - Interscrews or not, duralac etc

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FairweatherDave

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In the process of refurbishing my Westerly windows (main cabin long windows and forecabin portlights) and have got stuck into the research detail of refitting. I will be rebedding the frames with butyl tape between frames and hull. I can easily imagine the old interscrews ought to be replaced, several crumbled or span free as the windows came out. Interscrews are expensive and you need to get the right diameter and length. Domed headed SS nuts are an alternative but then you still need to be accurate on length, whereas ordinary self-locking ss nuts and trimming the bolt/screw after fitting sounds practical.
Q 1. interscrews or ordinary A2 grade SS nuts and bolts? Interested if anyone regrets not using interscrews.
Q2. Do I use duralac and if so how? Or should I be using some form of sealant in the frame hole as you would with a deck fitting ( I have read the hole should be nice and clear of butyl so the nut can be tightened up effectively - but not over tightening and squeezing out all the butyl. Window frames are aluminium and obviously the interscrews or whatever are SS.
Q3. The frame holes might need slight drilling out eg to M4. They are presumably anodised. Any thoughts?
Apologies for the detail and probable overthinking but opinions, tips and experience much appreciated.
 
I used Allen headed set screws on the outside and domed nuts inside, the trim was cut from 3mm marine ply. I don't reckon it came out too bad

1644939999238.png

The outside frames were pretty grotty, so I ground out the corrosion, filled with plastic metal and sprayed them with aluminium paint.
 
Stemar said:
I used Allen headed set screws on the outside and domed nuts inside, the trim was cut from 3mm marine ply. I don't reckon it came out too bad

View attachment 130462

The outside frames were pretty grotty, so I ground out the corrosion, filled with plastic metal and sprayed them with aluminium paint.
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That's very tidy! Sadly I sometimes settle for only good enough/ functional. But your dome headed nuts ( I read about previously) might easily be the solution.
 
Dave, I have just sent a PM you will find interesting.

Westerly used chrome plated brass interscrews that are 3.5mm in diameter and 10mm capacity. They used these as there was no chance of corrosion with the alloy frames. If stainless steel ones are used, then you must use Duralac or similar as a barrier against corrosion. Hadlow Marine had some s/s ones made, but the heads are too large compared to the original brass ones. The chrome plated brass ones of the correct size are almost impossible to find today from any regular supplier.
 
Concerto said:
Dave, I have just sent a PM you will find interesting.

Westerly used chrome plated brass interscrews that are 3.5mm in diameter and 10mm capacity. They used these as there was no chance of corrosion with the alloy frames. If stainless steel ones are used, then you must use Duralac or similar as a barrier against corrosion. Hadlow Marine had some s/s ones made, but the heads are too large compared to the original brass ones. The chrome plated brass ones of the correct size are almost impossible to find today from any regular supplier.
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Thanks Roger. Sent you a PM
 
JimC said:
What plastic metal did you use? (I have some crevices in mine where corrosion has eaten into the anodised aluminium)
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Obviously I am not Stemar...but in the WOA mag I saw someone coat their damaged aluminium with epoxy. Halfords sell quite a few products of the 2 part variety (Plastic padding chemical metal got me started ).

As I mentioned in my initial post I am quite interested in how to protect the aluminium where the anodising has gone. I will be painting the small portlights (again) but maybe just polishing the large frames with some wax so they retain their aluminium look. There maybe the odd spot I need to grind and fill. The spectacular corrosion was hidden in the joining plates of the two halves of the frame which look like some sort of screws into aluminium bars..... not much left of the screws and the bars are shot and need replacing completely.
 
Concerto said:
Dave, I have just sent a PM you will find interesting.

Westerly used chrome plated brass interscrews that are 3.5mm in diameter and 10mm capacity. They used these as there was no chance of corrosion with the alloy frames. If stainless steel ones are used, then you must use Duralac or similar as a barrier against corrosion. Hadlow Marine had some s/s ones made, but the heads are too large compared to the original brass ones. The chrome plated brass ones of the correct size are almost impossible to find today from any regular supplier.
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I replaced my old knackered Westerly 3.5m interscrews with M4 stainless plus 10mm long set screws. Drilled the frames and used duralac to isolate the screws/frames. I couldn't source any of the originals. I also used arbomast butyl as sealant.
 
neilf39 said:
I replaced my old knackered Westerly 3.5m interscrews with M4 stainless plus 10mm long set screws. Drilled the frames and used duralac to isolate the screws/frames. I couldn't source any of the originals. I also used arbomast butyl as sealant.
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Thanks Neil. I'm interpreting that as you re-used the original ones that were not knackered and just used new M4 ones to replace the knackered ones. The alternative is that you replaced all of them with M4 as they were all old and therefore liable to being knackered. :) .
(It is a genuine question as all my old original interscrews look their age and if some are shot will the others go that way too soon? For anyone fascinated by this dilemma the financial implications are to spend approx £80 as four windows need 80 screws if I replaced all with new)
 
FairweatherDave said:
Thanks Neil. I'm interpreting that as you re-used the original ones that were not knackered and just used new M4 ones to replace the knackered ones. The alternative is that you replaced all of them with M4 as they were all old and therefore liable to being knackered. :) .
(It is a genuine question as all my old original interscrews look their age and if some are shot will the others go that way too soon? For anyone fascinated by this dilemma the financial implications are to spend approx £80 as four windows need 80 screws if I replaced all with new)
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Replaced them all so they looked all the same. Much neater. Did it for two windows so 40 of them. If you are doing several windows and want to keep cost down but ascetics up then you could use all the old good ones where you can make up a complete set for a window. I preferred using bigger ones as there was corrosion around several of the holes and drilling got rid of some of it. The bigger interscrews have a bigger lip too.
 
JimC said:
What plastic metal did you use? (I have some crevices in mine where corrosion has eaten into the anodised aluminium)
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TBH, I can't remember, but it doesn't matter much - you could use any polyester or epoxy filler that sands smooth. I think the important bit is to grind out the corrosion so it's got something firm to hang onto.
FairweatherDave said:
I am quite interested in how to protect the aluminium where the anodising has gone.
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I just used a rattle can spray paint - Plasticote or similar. My joining bars were shot as well; I bodged something at first which was fine as the Perspex held everything together, but I never got them watertight until I used oversized Perspex, through-bolted, and cut the frames down to a flat trim.
 
Well it's swings and roundabouts! Thanks for your reply Neil.... I can see exactly the points you are making. Concerto has helped out so I will find out if reuse works. Duralac will be the key if I need to use stainless and drill bigger.....as will the butyl mastic if I don't get it right first time. As for the joining bars, only time will tell if my job works....I think they may do less work than in your original situation Stemar.....hope so....leaks are depressing!
 
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