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philipd
6 Posts |
 Posted - 29 Jan 2018 : 08:52:47
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I'm looking into converting the fixed aluminium windscreen on my Norman 24 GRP into one which I can fold down, preferably without having to buy new frames (aluminium seems a more sturdy material than wood!). Is it a reasonably easy job to do? I know I'll need hinges for both the front and side frames, since they'll have to fold down separately and then a way to hold the frames together once it's back up. Can anyone recommend the best size and type of hinges for this windscreen please?
I've attached a picture showing the current arrangement; since the picture was taken we have removed the aerial and relocated the horn, so clearance isn't an issue now. The design means that the front panels will have to fold down outwards/towards the bow and so they will have to detach from each other and vice versa when putting it back up. Would hooks or clips be good enough to hold the frames together and save having to faff around with screws?
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trevork
3949 Posts |
Posted - 29 Jan 2018 : 15:34:15
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| Lets hope Nigel (Woodwose) see's this. His boat is on the Norfolk Broads and has had this sort of modification. |
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df
United Kingdom
5994 Posts |
Posted - 30 Jan 2018 : 09:03:55
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Low bridge and plenty of throttle, job done.... Sorry forgot the fold back up bit. 
Check the angle when the screen rests on the handrails to make sure it won't sit just as high when it's folded, what is the airdraft with it up?
NBAS--The communal colostomy bag of the boating community.
 Visit leomagill.co.uk |
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philipd
6 Posts |
Posted - 30 Jan 2018 : 11:16:43
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quote:
Originally posted by df
Low bridge and plenty of throttle, job done.... Sorry forgot the fold back up bit.
Check the angle when the screen rests on the handrails to make sure it won't sit just as high when it's folded, what is the airdraft with it up?
NBAS--The communal colostomy bag of the boating community.
Visit leomagill.co.uk
Airdraft to the top of the windscreen is about 6'5. The handrails are a bit in the way, I'm a little worried the frames might stick out beyond the gunnel once folded out. The problem is I can't see how we'd be able to fold the frames 'inwards', because of the ridge behind the frames. |
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cliveshep
Thailand
1324 Posts |
Posted - 30 Jan 2018 : 13:37:59
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My Ocean 30 had a folding windscreen, the front was in 3 parts, the middle was hinged to fold out, the sides hinged on to the middle sides to fold inwards so you folded the lot outwards with the sides on top of the middle.
The two triangular sides folded inwards laying on the coach roof inside the screen.
What you need to do is make sure the bottom of your screen is straight because if it is curved you cannot hinge it.
My Ocean 30 here:
I also had a steel cruiser with a wooden wheelhouse that folded down, the front was in one piece, to enable folding the screen was straight at the bottom and fitted to a curved timber that fitted the coach roof profile and was fixed to the coach roof.
The sides on both boats were fixed in upright position to the front screen with one screwed thumb-turn screw each side, the steel boat had sliding sash window fasteners, the Ocean had something similar but meant for boats.
This one is ideal for you and is sold by Amazon UK.
On both boats the hinges were "piano" type hinges. Seaware will sell you marine grade continuous hinges here : https://www.seaware.co.uk/continuous-piano-hinge-stainless-steel-25mm-x-2m.html
or Seascrew will also sell them to you, they are a UK company:
https://www.seascrew.com/browse.cfm?&l=0000000769
Finally living the dream!
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Edited by - cliveshep on 30 Jan 2018 14:36:54 |
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df
United Kingdom
5994 Posts |
Posted - 30 Jan 2018 : 15:39:53
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If the hinges used had the pivot further forward of the bottom of the screen (equal to the height of the handrails) it would probably allow the curved frame to hinge and lay flat on the handrails as the bottom of the screen would lift when you fold it, one of the main screen sections would need an overlap to keep it all supported when back up (preferably with a stay inside).
Maybe slide the sides out entirely using a U channel with drainage holes or hinge to front sections so they fold inward and rest on top of main screens (if they clear the wiper motor).
Try a thin plywood mock up first to check geometry.
NBAS--The communal colostomy bag of the boating community.
Visit leomagill.co.uk |
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cliveshep
Thailand
1324 Posts |
Posted - 31 Jan 2018 : 06:12:53
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For Dave's idea to work you would need to fix a flat aluminium plate to the bottom of the window sticking out over the coach-roof say 70mm and hinge that to another plate underneath it fixed down to the coach roof.
Like my rough sketch here:
Finally living the dream!
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philipd
6 Posts |
Posted - 31 Jan 2018 : 07:38:40
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| Thanks for the replies. The bottom of the two front screens is slightly curved unfortunately; it basically fits to the profile of the roof so it's curved for that reason. |
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cliveshep
Thailand
1324 Posts |
Posted - 31 Jan 2018 : 08:10:43
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You would need to fit 2 "back-flap" hinges to each section to lift up clear of the roof curvature. Basically as my sketch but only 50mm wide so will lift clear of the curvature. From memory the curvature on a 24 is very small.
Finally living the dream!
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Edited by - cliveshep on 31 Jan 2018 08:18:25 |
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philipd
6 Posts |
Posted - 31 Jan 2018 : 09:36:21
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Thanks! I don't have a particularly good mechanical mind unfortunately which doesn't help but, two matching 50mm wide plates for each frame with one fixed to the roof and of a height to be level with the top of the handrail and the other fixed to the lower window frame, connected via a back-flap hinge for each frame? Have I got that right?
What would be the best way to allow one of the frames to overlap the other to keep it together? Currently the two frames are level together. |
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df
United Kingdom
5994 Posts |
Posted - 31 Jan 2018 : 10:20:56
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Work out the angle needed (cardboard templates are your friend) and get a sheet metal company to cut and fold a strip of aluminium to fit to the inside of one of the screens.
NBAS--The communal colostomy bag of the boating community.
Visit leomagill.co.uk |
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cliveshep
Thailand
1324 Posts |
Posted - 31 Jan 2018 : 12:00:05
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quote:
Originally posted by philipd
Thanks! I don't have a particularly good mechanical mind unfortunately which doesn't help but, two matching 50mm wide plates for each frame with one fixed to the roof and of a height to be level with the top of the handrail and the other fixed to the lower window frame, connected via a back-flap hinge for each frame? Have I got that right?
What would be the best way to allow one of the frames to overlap the other to keep it together? Currently the two frames are level together.
As Dave says, a piece of aluminium folded to the angle of the screen with the free edge turned out slightly is fitted to the outside AND inside of one leaf, forming a channel with the "toes" slightly turned out so that once the two sections are touching along their meeting edges the channel is gripping the closing section slightly to hold them together.
They are then located to the side frames the same way with a folded trim up the "join" to "weather" it and they are locked together with the thumb screw window fastener. The thumbscrew is fitted on the outside. and only one folded trim is used fixed to the outer edge of the front screen.
Finally living the dream!
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Edited by - cliveshep on 31 Jan 2018 12:04:26 |
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philipd
6 Posts |
Posted - 05 Feb 2018 : 02:25:17
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quote:
Originally posted by cliveshep
quote:
Originally posted by philipd
Thanks! I don't have a particularly good mechanical mind unfortunately which doesn't help but, two matching 50mm wide plates for each frame with one fixed to the roof and of a height to be level with the top of the handrail and the other fixed to the lower window frame, connected via a back-flap hinge for each frame? Have I got that right?
What would be the best way to allow one of the frames to overlap the other to keep it together? Currently the two frames are level together.
As Dave says, a piece of aluminium folded to the angle of the screen with the free edge turned out slightly is fitted to the outside AND inside of one leaf, forming a channel with the "toes" slightly turned out so that once the two sections are touching along their meeting edges the channel is gripping the closing section slightly to hold them together.
They are then located to the side frames the same way with a folded trim up the "join" to "weather" it and they are locked together with the thumb screw window fastener. The thumbscrew is fitted on the outside. and only one folded trim is used fixed to the outer edge of the front screen.
Finally living the dream!
Thanks. Do you have a rough sketch of this way of holding the two main frames together?
We've thought about just altering it so that the whole thing can lift off, but I don't want to have to spend 20 minutes fixing it back on upon leaving a tunnel - mainly in case it's pouring down! |
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cliveshep
Thailand
1324 Posts |
Posted - 06 Feb 2018 : 21:42:28
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I've altered my original suggestion to incorporate the method of locating the side screens to the front screens used on my Ocean 30.
It has one thumb screw each side you just screw up over the corner angle that is fixed to the front sections. Basically that is all you need because gravity holds the front windows in place and once the side screen is folded back up and the thumbscrew tightened the whole arrangement is effectively triangulated and thus secure.
The angles are either screwed or pop rivetted to the front screen.
Finally living the dream!
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philipd
6 Posts |
Posted - 07 Feb 2018 : 05:01:06
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quote:
Originally posted by cliveshep
I've altered my original suggestion to incorporate the method of locating the side screens to the front screens used on my Ocean 30.
It has one thumb screw each side you just screw up over the corner angle that is fixed to the front sections. Basically that is all you need because gravity holds the front windows in place and once the side screen is folded back up and the thumbscrew tightened the whole arrangement is effectively triangulated and thus secure.
The angles are either screwed or pop rivetted to the front screen.
Finally living the dream!
Thanks, you've been a great help! Once we have all the correct parts can it be done within a few hours? |
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df
United Kingdom
5994 Posts |
Posted - 07 Feb 2018 : 05:15:28
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In theory yes it could be done in a few hours but I would make sure you have a tarp handy and plan on it taking a week and the weather being crap, screens never come apart as easily as they should and there's always something rears it's head that needs more thinking about.
Don't forget Clive is on about an ocean 30 he did not a norman 24 so mouldings and angles will be different and will need considering, it's never as simple as transferring a design from one boat to another.
Mock it all up in cardboard first and offer it up to the boat to see if things will rest where you want them, then scratch your head for a while then go and have another think about it in the pub!
And remember a few minor discrepancies here and there could mean your canopy no longer fits right.
Don't be frightened off the job but don't rush into it too quick.
NBAS--The communal colostomy bag of the boating community.
Visit leomagill.co.uk |
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Topic |
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Norman 24 fixed windscreen to fold down
