Windscreen / Sprayhood

DaveS

DaveS

Well-Known Member
Joined
25 Aug 2004
Messages
5,484
Location
West Coast of Scotland
Visit site
My sprayhood is on its last legs and replacing it is on the list of things to do this winter. However, rather than just replace like for like I have been wondering about going for something more elaborate. The idea I am toying with is first fitting a fixed windscreen, to the top of which a new sprayhood would attach.

If flat glass / perspex / polycarbonate was used I think that 5 panels would do: rectangular in front, triangular at each side, and "shape-who's-name-I've-forgotten-with-4-different-length-edges" in between.

What I would like advice on is where to get the necessary bits to make such a thing. The sheet material is readily available - though there are differing views as to which is best - and I can find various sections of rubber seal. What to use as the frame, however? Some sort of U section extrusion would seem best but so far I've only found non anodised aluminium which I feel would just corrode. Plastic, if strong enough and immune to UV would be fine, but where to get it? And how best to join the panels together, bearing in mind the peculiar angles involved? I would even be happy to get the thing made professionally, if not too exhorbitantly priced: this would probably still involve me cutting up the framing to size on the boat then sending it back for assembly - a bit like making up a sprayhood kit. None of the advertised windscreen suppliers that I've tried were interested, however.

A completely different approach would be to get a single sheet of perspex or polycarbonate curved to the right shape - but I'm not sure how to go about even making a template for such a thing.

Any advice gratefully received.

<hr width=100% size=1>
 
It is possible to line bend acrylic (perspex). Method 1 uses an electric fire element in a sheet metal box, incorporating the dial for different heat outputs. Only use a low output because plastics are good insulators and the outside surface will bubble before the inside is soft if overheated. Then you need a jig to lay it on so it cools at the right angle.
Method 2 is really method 1a. I once had a rubber strip which had the heating element embedded - made it easier to lay on larger sheets.
Templates are a lot easier to do now that we can use strips of thin ply fixed together with gloops from a hot glue gun.
Don't know enough to say how polycarb or perspex would perform in service.
Do teh bending then scribe for a final fit aftwards.
There's a french boat in Boulogne, an Invicta I think that has a fabricated spray screen much as you describe. I didn't pay enough attention cos it could go on my to do list as well.
regards spuddy

<hr width=100% size=1>
 
Various sizes of Aluminium & Plastic U-Channels in different finishes are available from Chasmood Ltd. 01428 641655.

I run the company.

Martin

<hr width=100% size=1>
 
While polycarbonate is very impact-resistant it will scratch and cannot be readily polished out whereas acrylic can, I understand, though I've never done it. Due to the salt, sand and dust the environment is quite abrasive so plastic of any sort does fog eventually. Go for glass if you want it to look good for more than a few years; there is nothing like foggy windows to make a boat look old and unloved.

<hr width=100% size=1>
 
Most of the marine window people will make up custom windows for you. Use glass as it will last longer and not need replacing after a few years. My friend's Contessa 28 has 2 triangular side windows with a single front one, all windows in aluminium channel set into a custom made woode frame, works well. The wood frame conforms to the deck with holes thro' for lines etc.

<hr width=100% size=1>dickh
I'd rather be sailing... :-) /forums/images/icons/smile.gif
 
Did this about 6 years ago - very successfully. Built a mock-up windscreen, on the boat, using a smooth faced hardboard -with the good face on the inside thus forming a female mould. Braced it all using odd bits of timber and Gripfil making it strong enough to go home on top of the car.

Panels of 5mm MDF cut to the window shape and glued onto the inside of the mould
produced window panel rebates that allowed the windows to be flush with the finished moulding. After that, polished the mould, applied gel coat and laid up with glass mat.

Windows are of perspex sheet (ex sailing club notice boards and at least 20 years old) inserted with 6 self-tappers and a bead of silicone. On top of the windscreen a conventional spray hood frame and a mini sprayhood.

Total cost of windscreen was sub-£70 and 6 years on is working absolutley fine and with excellent visibility through the perspex windows, which have a silicone Rain-ex treatment twice a year (£3 per bottle and still on the first bottle).

Don't hesitate - do it, looks good on the boat too.

<hr width=100% size=1>
 
Thanks for that. Yeees. That is about as awkward as I feared it would be. Lots of scope for dripping plastic, burning holes... I haven't completely written this option off (particularly if I can get hold of enough plastic to allow one or more abortive tries before running out of material), but I have to say I am not enthusiastic. No reflection on the advice for which again many thanks.

<hr width=100% size=1>
 
I like the idea of glass for scratch resistance, but I'm a bit worried about (a) weight and (b) breakage. One of the manufacturers I contacted talked about toughened glass. Is this the same as that used for car windscreens before laminated became universal?

<hr width=100% size=1>
 
That is along the lines I had in mind but using 3 rather than 5 panels. Does that not make the top shape a bit too "square" for easily fitting on a sprayhood? Do you know what type of glass he used and what thickness?

<hr width=100% size=1>
 
Thanks very much - a most helpful reply and I particularly like the idea for the window inserts. I had thought of using GRP, but had been attracted by the thought of making the screen completely - or nearly completely - transparent. On the other hand a GRP design would be much less fiddly and probably stronger.

Of course if using GRP there's no real reason to limit it to just a screen - I can see possibilities for making a complete doghouse and eliminating the sprayhood. The biggest trick would be getting matching gelcoat otherwise it will look distinctly odd -and in fact few doghouses really look like they're an integral part of the boat.

Much food for thought!

<hr width=100% size=1>
 
Toughened glass is used for marine windows - laminated is frowned upon and plain is just for the foolhardy. A supplier of marine glass will cut each piece to size and etch it with the relevant standard on it to validate its nature (just like they do for vehicle glass).

It should not be tinted if the window is used for navigation, but for screens, dodgers, etc that can be looked over a high performance glass is worth considering if budget allows (looks nicer too, in my opinion).

John

<hr width=100% size=1>I am the cat but I am only 6.
 
I can see possibilities for making a complete doghouse and eliminating the sprayhood.

I think that you will find that it is not possible to make a doghouse that fits in with the profile of the boat until up around the 40 foot mark, if it is to extend over the companionway and the cockpit floor is to remain a reasonable height above the waterline (as it should on anything other than a very small yacht).

The height of the top of the doghouse is set by the height needed for a comfortable crouch downwards when stepping into the companionway - and the aft edge of the top needs to be sufficiently far forward so that when climbing out of the companionway one can lean aft so when go to step out to stand on the cockpit floor you don't knock yourself out on it. All very difficult to acheive on a smaller boat unless one is happy with a skyscraper type arrangement.

Hallberg Rassy have the art of screen design down to a fine art if there is a boat near to go and look at - else plenty of photos on thier internet site.

John

<hr width=100% size=1>I am the cat but I am only 6.
 
Strangely enough, one of the recent boat reports featured a boat with tinted screens. It was picked up on in the forums. It would be straight off my list as useless for night passages

<hr width=100% size=1>Me transmitte sursum, caledoni
 
Hi Brendan

Yes. We have tinted glass screens in a fixed dodger but are always careful to not navigate through them (managed to get the dodger so I can see over it easily when standing). Was a toss up type decision though, the pro being reducing the heat behind the glass (although Ships Cat finds it still a nice toasty place to lounge). Even in the day they can make red buoys, pole type daymarks, etc, especially hard to pick up from afar (as can sunglasses too).

John

<hr width=100% size=1>I am the cat but I am only 6.
 
If it helps for your weight calcs. 6mm Toughened glass weighs around 15 kilos per Sq. Metre.

Martin

<hr width=100% size=1>
 
Re: Dave S colour matching

You are quite right, possibilities are limitless. As others have said, I couldn't design a doghouse on my 32 footer that looked right, whereas the windscreen and mini-spray hood look very much like the Halberg Rassey/Najad designs, and is very acceptable. It may be interesting that, apart form racing, I almost never drop the sprayhood except in the hottest weather - but I cannot find an aesthetically pleasing way of eliminating it.

My 5mm perspex windows have stood up to quite a lot of heavy weather stuff over the past years, and were not young when inserted. They are light, cheap & effective and I find no need for glass.

As regards colour matching of the resin, my boat is Scandanavian and therefore a strange beigey/grey and very difficult to match. Solution, a pot of white gelcoat resin, a selection of appropriate gel colourants and one artist. The artist very quickly achieved an excellent match (using tiny amounts of colourant) and the receipe was retained for forthcoming projects, of which there have been several.

If you have a go, please remember to put a small return flange (roughly horizontal) onto the upper aft edge of the windscreen, as this provides a tremendous amount of strength & rigidity.


<hr width=100% size=1>
 
I've been following this one with some interest as I have been thinking about a similar project. Maxi, did you prepare the surface of your mould in any way or did you just put the polish direct onto the bare MDF? If so, what kind of polish did you use?

Also, should I decide to go that route, where do you get suitable thick toughened glass within an hour or so of Brighton......?

Paul.

<hr width=100% size=1>I used to have an open mind but my brains kept falling out.....
 
Re: PaulJ

Paul, I used a combination of white-faced hardboard (not quite mirror smooth) and MDF for the mould. Having set it all up, I gave it several applications of 'mould release wax' and allowed each coat to harden before final polishing. The wax is available anywhere that sells glassfibre components.

As for glass, my boat is a 30 footer and each of the windows is therefore pretty small and sits on a glassfibre flange, after quite a few years and a fair amount of green water on the screen, it is all going very well with no problems. Except, that I used 5mm perspex (second hand at that) which is lighter than glass, easier to work with, cheap & easy to replace if necessary - so I cannot give you any clues as to glass suppliers. Good luck. Phil

<hr width=100% size=1>
 
You must log in or register to reply here.

Other threads that may be of interest

S
Making Beading to fit a bend and having a 60° vertical profile.
Replies
5
Views
257
STATUE
S

Share this page

Top