Reliably Watertight hatch!

Nasher

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Sorry, this is a question about a RIB, cut me some slack.

One of the things I need to do to my 6.5M Ocean ‘The Nashers Revenge’ when I get access to her again is to change the Bilge pump. An easy job that is turned into a horrible one by access.

The RIB has an enclosed transom with a well below deck level where the Bilge pump and in hull transducer live.

The rear seat and transom moulding severely restricts access:



The well can just be seen to the left of the transom knee in this image



So getting to the bottom of the well is done with one arm only, at arms-length, in a very uncomfortable position from above through a small inspection hatch in the transom cover.
I've done it a few times over the years and it's not fun, especially trying to put a screw in etc when you can't see and have stuck the screw to the end of the screwdriver with grease or tape.
When the smaller Nashers were younger they could just about crawl in the covered space enough with a torch and see down the well to give instruction. But they are too big now.


This is a very old pic but it’s the only one I have. Ignore the since filled in cover panels on each side and the cable to the old transducer that was on the transom:


The small round inspection hatch is water-tight, which is great because the drain seen on the bottom right is below the water line when the boat is stationary.

What I want to do is replace the small inspection hatch with something bigger to improve access to the well.
But it needs to be watertight, or I’ll need to remember to put a bung in the drain each time I leave the boat stationary.
Even then waves sometimes come over the transom at rest.

Anyone had any good experience with a reliably watertight hatch that’s of a Nasher spec in terms of cost. Ie low?
I was recently shocked by the £200 cost of a round 8" Bailey plastic hatch which would only be a small improvement in access.
Either round, square or Rectangular, it doesn’t matter, and bigger than the 6” one there at the moment.

Thanks

Nasher.
 

pvb

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There are lots of rectangular access hatches which are said to be "watertight", but I wouldn't trust them to keep out standing water.
 

LittleSister

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Wouldn't it be easier to just replace the bilge pump with one mounted in a more accessible location?

It could (presumably) be outside the well (e.g. next to the oil filter), and just its inlet hose (with strum box on the end) and level switch in the well? The latter could be mounted on a stick of some sort, so they could be put into position and retrieved from the top of the well.

The existing hatch is presumably adequate for the rare occasions you might need to attend to the transducer.
 

Nasher

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Thanks guys

I can move the Bilge pump of course, but do still need access to the in hull transducer.
Having one on the transom never worked for me for various reasons.
Even the great quality Raymarine one I tried flips up at anything over 35knots.

The Boat does have two elephants trunks at deck level, but I'm always really reluctant to drill any holes below the waterline unless really necessary.

I feel the 'right' solution is a larger hatch.
I might have to get my TIG set out and build an Aluminium one with several latches I suppose.

Nasher
 

Nasher

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Just sat in the garden with a coffee and some of the suggestions on here sparked an idea.

I don’t need constant instant access down the hole, but do often use the existing small hatch to check how much water is down there, especially when I’ve just put the boat back on it’s trailer, and also to check how much rain water has got through the cover and collected whilst it’s sat on it’s trailer at the yard.

So, plan A.
I’ll weld up an Aluminium frame from extrusion with a lip, and with an aperture about 12” x 16” in the middle.
Then attach underneath some Stainless blocks or strips which will be drilled and tapped to use as captive nuts.
Several along each edge.

I can then lay up a flat Glassfibre sheet, or use what I carefully cut out, which I’ll screw down to the frame with a rubber seal using some nice button head stainless screws.
That provides the bigger access required occasionally.

For the more instant access required more often, I can leave the original inspection hatch in place in the bit I cut out, or add it to the new layup.

Oooo I love a project, but need the Plague lockdown to end as the boat is in a secure compound that’s locked up for the duration.

Thanks for everyones help.

Nasher.
 

Boathook

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Why not do something like this inspection plate that Tek-Tanks use, but put in the centre a small easy access inspection 'hatch' a bit like your existing. This would then (hopefully) give you the best of both. This would then mean no welding. All assumes that the existing layup is thick enough to thread for machine threads.

1586528194845.png
 

Pete7

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Nasher hi,

Is £35 within budget:

10'' Boat Yacht Round Porthole Opening Window Port Hole Portlight Hatch Marine 793207840585 | eBay

We have a whale 220 pump in the yacht. Its about 16lpm so mot huge but being a diaphragm is less likely to block with fluff, leaves etc. The pump is under a seat and there is 2m of 38mm pipe leading to the lowest part of the bilge with a strum box on the end to also reduce debris.

So once you have a decent sized hatch you can then mount the pump away from the bilge for access.

I did have one of these on one rib, bit like a mouse trap but did keep the water out.

WATERTIGHT HATCH BOAT YACHT SHIP FISHING HATCH | eBay

Pete
 

Nasher

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Hey Pete, good to hear from you, I hope you are well.

I hadn't thought about actual hatches like that.

More food for thought.

Boathook, unfortunately the layup is only about 3mm thick, so I need to add something I can screw into.

Nasher.
 

Pete7

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Boathook, unfortunately the layup is only about 3mm thick, so I need to add something I can screw into.

Nasher.

Well since this PBO how about this. Take one of the Missus's aluminium pans and cut the bottom off so you have a flat plate. Next cut out a large circle so you have a ring like a giant polo. Then cut a 2" piece out of the ring so that you have a C shape. This will now go through a hole that is smaller that the outside diameter of the c shaped ali plate.

Next step is a trip to ASDA for a polyethylene type cutting board. They are about 6mm thick and tough as old boots. I used one to mount a new chart plotter in the dash which was a different size to the RM C80. Cut to a round shape., a jig saw was hard work because if you rush it the plastic melts from the heat sealing up the cut. The Worx 54mm rotary cutter however made short work of it.

Clamp together and drill pilot hole through both. Tap ali plate and drill clearance hole in cutting board. Seal ali plate to underside of GRP with sticky stuff and make rubber gasket from piece of neoprene for the cutting board top piece.

Et volia, total cost £5 for chopping board, twenty hours self isolation in the garage making it, oh and £25 for flowers when Mrs Nasher finds her pan handle in the bin :rolleyes:

Take care mate

Pete
 
Last edited:

Nasher

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Just thought I'd update this.

I can't get to the boat yet to fit it, but I made this out of an old flat sheet of Fibreglass I had hanging around, a sheet of 1mm stainless that I cut and welded nuts to the back of, a sheet of rubber, and a spare small hatch the same as the one already fitted.
A quick check on what's going on down the hole can be done through the small hatch, but for any work that needs doing I can unscrew the panel.





Nasher
 

rogerthebodger

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Your rectangular hatch is generally how I do my access hatches except I fit set screws in the inside frame, washers and nuts on the outside, so the gasket is held in place when fitting the top but also if any of the set screws strip then can be replaced very easy.

I also have usd the same screw hatch 200mm dia on some jetty floats and found they did not seal properly as I used some silicon grease on the O Ring which allowed the screw hatch to seal properly . I pressure tested mine to check the seal
 
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