Original Lewmar fixed portlight – note the area obscured by the outer frame and rubber seal.
New fixed light – more light!
Like (almost?) all 25 year old boats Dulcinea had small leaks from most of the windows – 5 Old standard Lewmar opening portlights, 5 custom fixed Lewmar portlights and 2 Hull Lewmar portlights that fortunately don’t seem to be leaking. Looking on the web and in particular at the Moody Owners website, and from examining the leaks and the window frames its clear that most of the problems come from the fact that the aluminium frames of the topsides portlights are made in two halves with joints made with a plastic spacer centrally in each end. When the spacer ages it admits water, which then enters a hollow channel around the frame and emerges at the bottom. They may also leak at the joint between the hull and the frame where the sealant has failed, but this seems to be a secondary problem. There are various fudges suggested for fixing the frame joint leak, but fundamentally its a weak point and a bad design. It is possible to buy replacements for the opening portlights but not for the custom fixed lights. I had intended to send the complete windows off the Eagle Windows in Suffolk for refurbishment, and bought 3 blanks of 10 mm Perspex to make temporary blanking pieces while I had the lights out in relays. When I took out the fixed portlights to replace with my Perspex blanks I was shocked to discover how badly the openings were cut in the cabin sides, in particular in places round the ends the overlap between frame and cabin side was no more than 3 mm.(1/8 inch). Putting the temporary Perpex in without the frames using Butyl tape showed to my surprise how much more light they admitted to the cabin without the frame. The nett result was that I decided to fit new windows in the fixed portlights made of 10 mm tinted Perspex that were 3mm bigger all round than the aluminium frames. The essential design was to use the inner aluminium frame to hold the Perspex in from the inside, using tapped M5 holes in the Perspex. Since I wanted the threads on the outside to be exactly flush with the outer surface of the Perspex for aesthetic reasons and the thickness of cabin sides varied by a couple of mm I couldn’t simply use screws from frame to Perspex, at least without tailoring every screw to fit, so I devised the method described below using tapped spacers with studs threaded into the Perspex and spacers, and short screws through the frame into the spacers. Since Perspex is prone to stress cracking its important not to stress the tapped holes, but using butyl tape as the sealant between Perspex and cabin side it is not necessary to screw the window in very tightly – butyl tape grabs surfaces and will remain pliable so that it doesn’t need to be tightly squeezed in the joints – in fact its better to tighten it up gradually and let it flow over time to reduce the stress on the fixings. I put the studs in the Perspex using High Strength Loctite to spread any stress over the whole thread, it also helps to make sure the studs remain flush on the outside.
N.B. inner screws should be 16mm and can be Pan head or Button head as you like! I prefer button head screws as they take a hex wrench.
Here is a composite unedited 10 minute video of removing the Lewmar opening portlights – with a clip at the end showing the new fixed window offered up.
Here is my guide to the job which excluding preparation of the Perspex and gathering parts took around 3 hours per window:
You’ll need:
Filling knife with thin, very flexible blade
Crosshead screwdriver to remove old inner frames.
Old cut down small kitchen knife
Old chisel and bit of thin ply or old table mat to help prise window out
Hex key for button head screws
Old Kitchen Scissors to cut Butyl tape.
Perspex cut and polished – 10mm light tinted – Cutmy.com
CT1 Multisolve aerosol – cleaning and lubricant -Toolstation
Green kitchen fibre abrasive pads
Isopropyl Alcohol for cleaning.
Loctite High Strength
Rounding over bearing guided router cutter 8 mm or 5/16″
Moody 40 needs approx 100 of each of the fixings for 5 lights;-
M5 20mm studs -preferably 316 / A4 stainless, or 304 / A2 – ebay
M5 spacers tapped through ( probably 304 is all you’ll get!) ebay- or better turn up out of 10 mm PET rod or 3D print and tap from both ends with a small overlap in the middle.
M5 x 16 mm button head screws for inner frame (316 or 304) – use Pan head if you prefer. You may find that the 16mm is too long for one or two places due to thin cabin sides, so a few 12mm screws might be handy and save having to file a couple of mm off a 16mm screw!.
5mm Nylon washers under heads of inside M5 screws. Farnell
3M Dual (sort of Hook and loop tape substitute as used by Lewmar) to fix plastic inner back on.) ebay
Black Butyl tape 20mm x 3 mm or thereabouts. (Cut in half to 10 mm) Amazon
For the opening lights you will need 20mm screws.
N.B. the studs and spacers on ebay come from China and take a week or so to arrive!
To remove the old portlights remove the inner plastic cover (take care not to break it – it may be held on with 3M Dual tape or glue) and the inside screws holding the interior frame. To remove the aluminium frame use a very thin filling knife (50 mm wide is good) and work a corner somewhere in between the cabin side and the aluminium frame. Spray a little CT1 Multisolve on the joint – it helps to lubricate the blade, then tap the handle of the knife with a small hammer and drive it round the entire window – the corner of the knife should be flexible enough to bend to fit the gap. There may be some adhesive between the cutout sides and the rebate on the frame – take the filling knife and drive it round the gap from the inside of the boat – you might need to use a cut down kitchen knife to get round the corners. If you have done a good job of the cutting, a chisel should slip between the cabin and frame with the back against the cabin side and a bit of card for padding should be adequate to lever the window off – If it doesn’t come by gentle persuasion recut the joints.
You’ll need to clean up the cabin face with Multisolve and a green kitchen pad frequently replaced, and may need to make good defects in the cabin outer gelcoat and the exposed interior packing of the cabin side sandwich. I smeared white Sitka sealant round the edge of the sandwich to make it look neat,
Note that the fore and aft fixed lights on Dulcinea are slightly different sizes although it hardly shows. Also the inner frames for fixed lights are all slightly different so you need to keep Perspex and inner frame together and mark the top and inside of each. The aft light is rectangular with approx 72mm diameter corners, and the fore light is slightly narrower ( 3mm?) and is tapered by about 3 or 4 mm towards the front.
Making the Perspex windows;-
You can order cut Perspex with rounded corners and polished edges from Cutmy.com , you can then round off the outer edge with a bearing guided rounding-over cutter and polish with very fine wet and dry paper (to 1200 grit) and buff on a wheel or hand polish (I’m not sure if Cutmy.com will do the rounding over for you – they say they will make boat windows).
Having got the Perspex shaped place the old inner frame on it centrally and mark the up position on the Perspex ( the frame joint goes at the bottom, Then mark through the hole positions accurately and drill through 3 mm holes as pilot holes, and follow with a 4.5 mm drill lubricated with water or Multisolve (not oil) – make sure you drill accurately at right angles to the Perspex surface – use a drill press or a guide of some sort as otherwise the screws wont align and there will be stress on the threads. Then tap the holes M5 using a No2 tap – either by hand or in an electric drill set to minimal torque. Be careful with this – ideally only take the tap in far enough to just enable the stud to screw in.
Screw the studs in from the inside of the Perspex having put a small amount of Loctite on the sides of the thread at the end until they are exactly flush – make sure you don’t smear Loctite about! Leave for a few hours for the Loctite to bond. Then screw the spacers onto the studs firm finger tight. Now offer the window up to the opening and work out how much clearance there is up and down and end to end between the spacers and the opening, so that when you offer up the window with the Butyl tape in place you can locate it correctly before bringing the butyl into contact with the cabin side.
The essential point of the following method is that the butyl must keep at least one layer of paper stuck to it until it goes onto the Perspex or it will stretch and you won’t be able to get an even layer of sealant in the joint (believe me!) – if it touches anything it will stick and then you will find it impossible to get an even thickness. Cut off about a meter of the Butyl tape and peel off the backing strip and throw the Butyl tape itself away and cut the backing strip in half lengthways ( I know it sounds daft). Now unreel enough butyl tape on a clear surface to go somewhat more than halfway round the edge of the window and stick one strip of backing paper carefully over the exposed butyl surface, and cut down the middle of the butyl with the scissors. Clean the edge of the Perspex with Isopropyl Alcohol (IPA) and allow to dry. Now peel the under side of the Butyl gradually as you work round the window, only removing the top side when you have to to navigate the corners. Make sure the tape is of fairly uniform thickness all the way round and fill any really obvious gaps.
Now offer the window up to the opening, holding it clear while you ensure that it is in the predetermined position, then when you are sure, push it onto the cabin side. It will grab pretty firmly so you wont get a second chance! Press all round the frame firmly to seat it, and retire inside. Offer up the same frame that you used to mark the holes( they are not all drilled identically), and insert the 16 mm screws through into the spacers with a nylon washer under the heads. don’t tighten at this stage. When all the screws are in go round and tighten them till they begin to come tight, then repeat going round tightening them a bit more. Over the next hour tighten the screws a few times, gradually increasing the force on them but never really tightening them down hard. I found a couple of 16mm screws bottomed onto the studs and had to find a 12mm screw to make it work.
Once that is done, use 10 mm bits of the 3M Dual tape to attach the plastic cover to the aluminium frame – I’d cleaned the bits off the frame when I’d cleaned up the frames.
Optionally you can trim off the excess Butyl tape that has overlapped the Perspex, probably cutting it off with a blunt knife with Multisolve as a lubricant. Warning don’t get WD40 near the Butyl tape – it becomes super sticky (I haven’t done this yet).
Having saved a pile of money making the fixed portlights over the cost of refurbishing them, we blew it on replacing the 5 opening size 4 ‘s with new ones, the only slight problem here being that the opening lights were a very good fit in the cabin sides and the rebate was well bonded so I had to strip off the hinges and catches to be able to cut round the rebate from the inside and release the frames. I also had to file the openings as the new size 4’s were very slightly bigger that the old ones.
I had to remove the catches and hinges from the opening lights to cut the rebate – see video -but otherwise no problem, except that the new frames were very slightly larger than the old – by the equivalent of a few file strokes on the cabin side. They don’t have a rebate in the same way, so you don’t have the option of a backup rebate seal as with the old pattern. I decided to use a grey Butyl sealant to seal the frames in – it does get squeezed pretty thin as the window is screwed in, but the frames have a shallow groove all round which should hold a bead of sealant.