Model Boat Mayhem - Forum

Dry Dock / Shipyard: Builds & Questions => Yachts and Sail R&D: => Topic started by: stringer on October 12, 2016, 09:29:06 PM

Title: hatch covers
Post by: stringer on October 12, 2016, 09:29:06 PM
Hi
I am asking for help in constructing hatch covers, I am at this stage in my scratch build of a VO 60 ocean racing yacht, I have seen yachts with plastic covers with tape holding them down and would like something more substantial and as low as possible to the deck creating its own watertight seal able to be removed and replaced easily, a problem that's keeping me awake at night and holding up the build. I would appreciate any help you guys can give me, this is a big forum, I am hoping there are clever people who have also met this problem, and can help me here.
regards Geoff
Title: Re: hatch covers
Post by: unbuiltnautilus on October 12, 2016, 09:55:02 PM
Well there is a challenge. If your decks are flush with no coaming I would suggest something like this. A flat hatch with a tongue that can tuck UNDER one end of the hatch. At the other end, a sticky up threaded stud, mounted through the main deck and through the removable hatch. This gives you the basics of a hatch with just one screw down fitting.
That's the good news! Now you need to take into account some sort of foam seal, which is soft enough not to deform when tightened down, also some sort of stiffening to the top of the hatch, for the same reason.
You could go with some sort of low profile, laminated hatch, the layers providing the stiffness.
Your sticky up thread could be disguised with a ships wheel and up stand, or satellite dish mount or some such..
Title: Re: hatch covers
Post by: stringer on October 13, 2016, 12:00:37 AM
hi unbuiltnautilus
I like this idea, have ordered 3/16 ply to make hatch covers, the side view of  the hatch cover in the centre would be flat on the deck, whilst looking from the front of the yacht the side edges of the cover would be higher due to the curve of the deck, I am now thinking if I can steam the cover, and form it to follow the curve of the deck, and overlap the hatch opening by 1/4" all round to allow for the seal I can use your idea of securing it down.
 I will need to wait for my wood to be delivered, and let you know if it works.
thanks for replying   
Title: Re: hatch covers
Post by: Netleyned on October 13, 2016, 10:13:17 AM
Make sure you use closed cell foam as cheapo draught excluder foam
acts like a sponge and soaks up water which in turn keeps the wood wet
long after you have left the pond.


Ned
Title: Re: hatch covers
Post by: stringer on October 13, 2016, 10:26:42 AM

hi Netleyned (http://www.modelboatmayhem.co.uk/forum/index.php?action=profile;u=9233)
thanks for your reply, as I was going to use draught excluder, but will now look for closed cell ?, have not heard of this before, any idea  where I can obtain it
regards Geoff
Title: Re: hatch covers
Post by: unbuiltnautilus on October 13, 2016, 01:12:57 PM
Closed Cell Neoprene is used in the marine industry for hatch and window seals, you may end up with a 30 metre roll though!!
Title: Re: hatch covers
Post by: Crossie on October 13, 2016, 01:20:11 PM



 You could get something suitable here  http://www.corseal.co.uk/products/neoprene-epdm-closed-cell-strips-self-adhesive
Title: Re: hatch covers
Post by: stringer on October 13, 2016, 04:50:29 PM
HI Crossie
never having used this product will it compress similar to draught proof tape, if I buy it I will use 3mm x 6mm, thanks for your info
Geoff
Title: Re: hatch covers
Post by: Crossie on October 13, 2016, 07:15:10 PM



        edpm sponge tapes are not as soft as the sort of cheapo plastic foam tapes that are sold on the High Street which take very little pressure to compress from 8mm or so down to less than 1mm, but will last much longer and seal better. A good idea is to form a very narrow ridge around the underside of your hatch so that it presses into the centre part of the seal- -imagine a knife edge creating a high pressure ring - -this will create a much better seal.


 Anyway at 1.80 and a bit of postage it's not exactly a big deal I would think
Title: Re: hatch covers
Post by: Nemo on October 13, 2016, 09:09:17 PM
I used this neoprene to seal a 'virtually' flush radio access hatch - not a drop gets in! They may do a 1mm thickness also. :-))

http://www.ebay.co.uk/itm/261873677001?_trksid=p2060353.m2749.l2649&ssPageName=STRK%3AMEBIDX%3AIT
Title: Re: hatch covers
Post by: hammer on October 20, 2016, 10:14:38 AM
Here is my solution for a hatch on a flush deck. Almost invisible when shut & 100% water prof. The rubber cost nothing being from old plastic window. Just strip out the seal.
Title: Re: hatch covers
Post by: JerryTodd on October 20, 2016, 02:56:51 PM
I've seen several yachts make good use of snap-lid food containers, ie Tupperware and the like.  You get to burp your boat that way.  ;)

I have two flush hatches on Constellation a little like Hammer's that function as shown in the attached drawing.  One photo shows the framing of the opening with the hatch near-by, the next shows when the deck was laid.
Title: Re: hatch covers
Post by: stringer on October 20, 2016, 10:00:03 PM

Hi Jerry
thanks for your input, when I started my hatches they were raised above the deck and would be higher than the deck, the covers were made to sit over the hatch like a box cover, this looked good on my previous schooner, but not on the VO 60 racing yacht I am building now as it needs to be sleek, I have reduced the sides of the hatch to be level with the false deck, and then surrounded the hatch with similar thickness as the deck planking, my hatch cover now sits on the deck with a box shape inside locating the cover, the seal which I have to find yet will lie between the cover and the deck, I see your cover sits level with the deck,
do you have a seal and if so where is it located???,
if you do have a seal what are you using please??
regards Geoff
I will be using your method of holding the hatch cover in place
Title: Re: hatch covers
Post by: JerryTodd on October 21, 2016, 07:33:24 PM
A bit of thin weather-stripping on the ledge.  Unlike a sleek yatch, Stella isn't going to be dipping the rail constantly, so waterproof isn't so much an issue, some water-resistance is all I'm after.
The main hatch work in the same manner, but it's inside a coaming.  The "battery hatch" where the capstan & skylight are may get a o-ring stretched around it as it slips inside like a reverse box lid.
Title: Re: hatch covers
Post by: hammer on October 22, 2016, 09:42:52 AM
My hatch is screwed down on the four corners totally waterproof, as the rubber is compressed all the way around. the screws are under a loose plank on ether side. Not that loose a press fit more like. Hammer   
Title: Re: hatch covers
Post by: stringer on October 24, 2016, 01:17:06 PM
Hi Hammer
I like your method for your hatch cover, but I have made mine to fit on top and flush with the deck , to change now would involve a lot of work, so I will continue my search for a compressible seal that is not too thick, whilst I fibre glass the hull, and finish off the deck planking, next problem will be the masts which I will be looking for hollow fishing rods.
thanks for every ones contribution
Thanks Hammer will keep your Idea for future builds
Great forum thanks again every one
Geoff 
Title: Re: hatch covers
Post by: WeymouthJohn on August 02, 2017, 10:15:53 AM
I'm new to all this boat modelling but I've used wetsuit neoprene in the past for thin sealing strip. Very cheap to buy in the quantity you'd be needing .... almost an offcut from our local wetsuit maker.

Title: Re: hatch covers
Post by: roycv on August 02, 2017, 11:04:26 AM
Hi I must have missed this at the start.  I have been doing flush decks for years now.  The method of holding the deck down mentioned above will work.
My seal is made from cycle valve tubing which you can buy in lengths, cut to size  with a smear of vaseline all round.  On one of my models I used the large bollards / winches (Americas cup yacht) 4 off, on the hatch, each one had a brass cheese head soldered to base of bollard at the head.  Then some stiff brass cut like a single propeller blade was lock nutted on the screw thead and this acted as a coarse thread to latch with a piece of brass shim underneath.  Less than a quarter turn locates it.
I also connected 2 of the bollards to the charging point of the battery.  So with 2 croc clips I could charge the battery in situ.
Hope this helps,
Roy
Title: Re: hatch covers
Post by: spearfish99 on August 02, 2017, 01:15:23 PM
next problem will be the masts which I will be looking for hollow fishing rods.


   Have a look here    http://www.easycomposites.co.uk/#!/cured-carbon-fibre-products/carbon-fibre-tube

  Also for fixing down hatches the little flat high "grab " magnets that you can buy off Ebay can be extremely useful. 

    http://www.ebay.co.uk/itm/8-Rare-Earth-Neodymium-Magnets-N50-Aeroplane-Canopy-Hatch-10mm-x-2mm-fpv-glider-/152381543290?hash=item237aa5d37a:g:rHEAAOSw1ZBUxqBX