Making engine access through cockpit floor - good/bad practice?

[Robert Wilson]

Is it practical/completely bonkers to install a hatch in the cockpit floor to get at the engine beneath?
It would need cross-bracing to give strength and rigidity to the hatch itself, but would it damage/weaken the integrity of the boat*.
Any suggestions as to bracing to maintain full integrity?

Ideally the hatch opening would be as large as possible to give best access, but even a couple of feet square would greatly help repairs and maintenance

CO8's thread re "Sourcing white GRP sheet etc" got me thinking.

* Boat is 9m/5.5 tonnes Javelin30, built 1970's by Marcon - like a battleship

 

[doug748]

Thought about this - not actually doing it but what I would do if I had to do it, if you see what I mean.

You see so many rusty engines which have been ruined by leaks; I would fit a low profile Lewmar (or similar) hatch and make good teak duckboards to ensure the thing would not be walked on. The disadvantage would be cost, the advantages: light in the engine bay and quality waterproofing. Nothing would induce me to experiment in this area cos the degree on jeopardy is too high, for me.

The floor would need to be braced, certainly side to side. Tricky work, in a very tight space, working overhead.

 

[MOBY2]

Morning, I too have a Marcon built battleship Trident 24, she has a hatch in the cockpit floor, however I would make the following recommendations ... Check the floor has strengthening beams glass in underneath, mine were mahogany so yours may will be the same as Eric never scrimped on anything ... Buy a decent hatch, it will work out cheaper than trying to make one... Make sure you have a good strong floor over the new hatch, this was the down fall off the old hatch mine had, the previous owner had taken a cross beam out of the hardwood flooring, this made it weak over the hatch which subsequently cracked allowing water to get below, all sorted now thankfully, hope that helps a bit.

 

[richardabeattie]

Sabre 27 have such a hatch and it's fine if it is re-sealed with double sided tape after it has been opened

 

[[163233]]

Go all the way and put in an outboard well.

 

[Sticky Fingers]

Structurally might well be OK especially if well braced etc, but I'd be worried about ensuring it's flawlessly and permanently watertight. If you took a wave into the cockpit you wouldn't want it to exit via the engine room...!

 

[pvb]

My old HR352 had a hatch in the cockpit floor, underneath a teak grating. It was the only way of getting the engine out. However, the opening was strongly reinforced and the hatch itself was very rigid. It was held down by about 20 countersunk machine screws around the perimeter, and the whole joint was sealed with silicone.

 

[bristoljim]

Make up GRP or epoxy glass reinforced ply beams & bolt through cockpit floor & structure either side.Good quality hatch gives very useful light & access.
Jim

 

[Deleted member 36384]

Similar to pvb's HR352, my Rival 41C has a hatch almost the full size of the cockpit sole. The hole is edged outboard with a gutter that runs right around the cockpit sole, about 3" deep, 2" wide. The gutter will no doubt add to the stiffness of the GRP edge around the opening. There is no "cross bracing" underneath. If you think about the sides of the cockpit, then the gutter is like a small ledge which the hatch sits on. I guess most of the load is transferred into the sides more so than a bending moment on the edge. The hatch also has the wheel pedestal mounted on it. Hatch is about 2" thick and has a stiffeners moulded into the underside, both longitudinal and athwartship.

 

[BrianH]

My old HR352 had a hatch in the cockpit floor, underneath a teak grating. It was the only way of getting the engine out. However, the opening was strongly reinforced and the hatch itself was very rigid. It was held down by about 20 countersunk machine screws around the perimeter, and the whole joint was sealed with silicone.

My HR94 (sold earlier this year) also had a hinged cockpit sole, the forward half, that could be lifted for engine access - although very heavy. It seated on a raised rim in the cockpit floor moulding, which met foam rubber strips on the floor section. It was not watertight, in fact, the cockpit sole edges drained into the channel formed by the rim that had drain tubes and sea cocks on both forward sides.

There was never water entry into the engine area bilge and, of course, engine access was excellent as the companionway steps and aft bulkhead also removed for exposing forward engine components from the cabin. It was possible to step down and stand on the flat bilge sections next to the engine bearers and work quite comfortably.

However, with a hard doghouse, the cockpit was not vulnerable and rarely shipped any water whatsoever.

 

[PuffTheMagicDragon]

I had one on my old Centaur. Never had any problems in fourteen years. It was a GRP lid that fitted over a moulding in the cockpit, a sort of coaming that was some 50mm high. There was a rubber strip all round that made the lid watertight. The lid was held down by 4 toggle screws. I found it very useful when adjusting the control cables, gearbox, water trap, coupling, shaft packing and a host of other things.
I had thought of making a similar arrangement on my present boat, an old Centurion 32, where access to the items that I mentioned above is awkward - to put it mildly - because I need to first empty a deep locker in the cockpit and would then need to wiggle the upper part of my body over the two batteries that are placed right net to the opening. Unfortunately I never got round to make it and now I will not bother because of my age (next Wednesday I will be 73) and I am not as agile as I used to be.
In both cases, the 'lid' would be beneath the wooden grating of the cockpit sole and is more than enough to be protected, even if someone jumps heavily down from a cockpit seat.

 

[Robert Wilson]

All helpful and encouraging replies, thank you one and all.
IF I go ahead, I shall employ the services of a chap locally who does fibreglass work; and shall let him read this thread first

My main concern was that by cutting-out a reasonable chunk of cockpit sole would I in any way weaken the hull stiffness. With properly made and installed cross-braces, it looks from your responses, that it wouldn't :encouragement:
I also like the idea of a wooden grating to protect it, and hopefully provide good grip.

I would want, if feasible, quick access to the area so I'd like to go for a hinged hatch with a couple of "lift n turn" hatch locks.
I doubt I'll get round to it this winter, but the thought of easy access to the back of the donk is mighty appealing!
The grandchildren's Christmas pressies may be skimped.........:eek-new:

P.S. The BIG downside to doing this would be the encouragement to replace the engine...........:hororr:

 

[Refueler]

Similar to pvb's HR352, my Rival 41C has a hatch almost the full size of the cockpit sole. The hole is edged outboard with a gutter that runs right around the cockpit sole, about 3" deep, 2" wide. The gutter will no doubt add to the stiffness of the GRP edge around the opening. There is no "cross bracing" underneath. If you think about the sides of the cockpit, then the gutter is like a small ledge which the hatch sits on. I guess most of the load is transferred into the sides more so than a bending moment on the edge. The hatch also has the wheel pedestal mounted on it. Hatch is about 2" thick and has a stiffeners moulded into the underside, both longitudinal and athwartship.

My Sunrider 25 has similar ...

The whole cockpit floor lifts up ... original was basically a 3/4" slab of Marine ply with non-slip decking glued on ... about 4ft long and 2ft wide. It has as quoted - a gulley that runs round outside of the raised part that carries the 'floor'. The drains are in the aft corners of the gulley.
After 40 odd years - I replaced it with new marine ply that has a fixed non-slip surface one side and smooth on other.

Under this - there is a cross bulkhead that is only really there for support of shaft tube.

The raised ridge that it sits on has draught excluder self adhesive foam strip applied to seal when in place. There are 4 stainless bolts, one each side / end, that bolt through the plywood then through the ridge into thread-tapped plates bonded in.

This is about best shot I can find to give an idea ...



Here's making new one that I replaced as well few years later with thicker version ...





The main point is that most boats built in the 1970's were overbuilt and as OP says - battleships !! It was common for boats to not have sandwich GRP form ... ie my Sunrider is 50mm solid GRP hull ... I know that from cutting a through hull for speed log. It ruined 3 hole cutters doing it !
Many were also lacking self draining cockpits !
But the common practice of having bunks / storage going under the cockpit benches made for strong structures.

 

[Stemar]

I'm also thinking vaguely that I'd get better access to behind the engine with a cockpit hatch; the only way in at the moment is over the top of the engine. I did it 15 years ago, but I rather think I'd either get stuck on the way in or end up staying there if I tried it now. :disgust:

I've got as far as thinking that I'd need a rectangle with rounded edges and reinforcing all round - probably a metal tube about 25mm diameter, glassed in. I'd also want a gutter to catch leaks, with a drain into the bilge, or an external drain if it turns out to carry more than the odd drop. The amount of work involved on a boat that's worth little means it's unlikely to happen until I absolutely have to get in there and can't find someone to pay to do the job!

 

[Baggywrinkle]

Rainwater .... you don't necessarily need to think about sealing against the odd wave sluicing into the cockpit, it's rainwater that will be the real killer.

If the boat wasn't designed to have a hatch in the cockpit sole then whatever you build has to be rainwater proof - the drainage needs to go overboard with no chance of any puddling round the hatch - it will find its way in - and it's amazong how much rainwater can collect over a short period of time.

Have a look at this ....

When It Rains, Boats Sink ...

Example #1: 25-foot Sportfisher
The scuppers were below the waterline at the transom and just at the waterline in the cockpit. Directly forward of the port and starboard side scuppers were hatches that led to the bilge. The hatches were not dogged down, and the manufacturer had made no attempt to seal them. Water failed to drain out of the scupper system fast enough, and the boat began to take on water through the leaking hatches into the bilge, overwhelming the bilge pump. As the boat became heavier, the scuppers submerged under water, and that was that.

https://www.boatus.com/seaworthy/magazine/2016/april/when-it-rains-boats-sink.asp

 

[Poignard]

 

[LittleSister]

I think by focusing on cross-bracing, perhaps the need/opportunity for vertical support is being overlooked.

My LM27 has the almost the whole of the cockpit sole lift out in two parts (the foremost over the engine), but it all seems very rigid. The lifting parts are only wood about 3/4" thick, with lightweight acoustic insulation on the underside. The cross-bracing is lateral ply bulkheads across the front, near the middle and rear under the cockpit sole and supporting it. The whole length of the sides is also supported, in this case by longitudinal GRP bulkheads (these are also walls to the fuel and water tanks).

Access to the top and rear of the engine is excellent, but to the lower sides and front not so good (the engine is larger than standard).

Later LMs have a broadly similar arrangement but greater use of GRP, and the engine is further enclosed in a GRP case for sound and water-proofing.

 

[simonfraser]

having just fitted a proper deck hatch after removing a plexiglass screwed down access panel, this is crucial imo:
lid over lip & drainage, as in one of the above posts
http://www.ybw.com/forums/attachment.php?attachmentid=82094&d=1575202241

 

[PetiteFleur]

You need a raised lip on the floor to make gutter all the way round, say a 2" wide and a lip 1½" high,, bolted to the floor with 6mm countersunk screws, rubber sponge rubber for sealing. I would bolt down in each corner with TIMAGE hatch bolt downs - I used these http://timage.eu/marine/hatch-locking-devices/112-11HATCHLOCKING.html a bit expensive but effective. If you hinge it say halfway along, rear half bolted down, front half hinged and secured with two of the lock downs.

 

[Refueler]

Rainwater .... you don't necessarily need to think about sealing against the odd wave sluicing into the cockpit, it's rainwater that will be the real killer.

100% true ....

My boat when it was in UK ... I only got back for a few weeks each year to use it ... I called marina to launch the boat so I could have a few days sailing. I'd changed my contract to dry berthing with 3 liftins per year.

I got to the boat and found it on a strange pontoon and extremely low in the water. While I was looking ... yard manager approached and said they moored her there because the boat was unstable and they couldn't risk moving her further. They had not opened up to see why ... its all to do with claims and responsibility ... they do what you ask and nothing more.

I opened the hatch and she was 1/2 full of water ... all FRESHWATER ... not a hint of seawater at all.

Basically the cockpit drains had blocked with leaves and water had been collecting and seeping under the cockpit seals into the bilges.

Wife and I spent the day pumping her out ... she was left open to dry out as best as possible. Over the next week - I tested engine and gear .. all seemed ok. Even took her for a sail ...

Next time out - wife, friend and his fiancee with me ... we went over to Isle of Wight .. all fine. Next day to go back to Hayling ... engine wouldn't turn over.
Sailed her back to Hayling ... another boat took Wife and the other two ashore leaving me on board as she'd run aground ..... not my fault I add ! But that's another story.

I managed by use of Genny and anchor to get my way to the marina and alongside. Anyone who knows HYCo will know to do it purely by sail is not so easy !!

Next day - Alan - Diesel guy at HYCo had a look and declared my trusty old 4-99 seized solid ... probably from the water that had flooded the boat. Even though we'd changed oil etc. - it hadn't saved it.

Luckily there was a 4-107 which had been taken out of another boat laying at back of yard ... HYCo let me have it for budget price and it was fitted in replacement for the 4-99. (Many years later that 4-107 is still proving to be an excellent engine in her).

Sorry about the long story ... but just goes to show how important clearing that rainwater can be ... that flooding cost me overall about £3000 with replacing engine, few wood panels and various gear that was underwater ...