Non draining section under stern gland?

[goeasy123]

On my N400 there's no limber hole in the space under the engine and stern gland. On the sides there are the engine bearers and on the front a low glassed in bulkhead from hull to sole level. When the Volvo gland leaks, as they are prone to do this sump fills up and bathes the bottom of the engine in salt water.

Is the lack of limber hole a 'design feature' with some purpose? Are there any downsides to making a limber hole, where is the best place to do it and how?

 

[Poignard]

Not sure if it's the same thing as you are talking about but Twisters have a deep well under the forward end of the engine into which any bilge water, or leaks from the engine, drains.

The bilge pump suction strum box(es) are at the bottom of this sump.

 

[graham]

The limber hole is omitted to stop dirty water contaminated with stern tube grease or god forbid engine oil leaks running into the rest of the bilges.

 

[Tranona]

On my N400 there's no limber hole in the space under the engine and stern gland. On the sides there are the engine bearers and on the front a low glassed in bulkhead from hull to sole level. When the Volvo gland leaks, as they are prone to do this sump fills up and bathes the bottom of the engine in salt water.

Is the lack of limber hole a 'design feature' with some purpose? Are there any downsides to making a limber hole, where is the best place to do it and how?

There is something wrong if your Volvo gland leaks except when burping it after launching. Even this can be avoided if you replace it with a Radice seal which is vented above the waterline.

 

[Poignard]

There is something wrong if your Volvo gland leaks except when burping it after launching. Even this can be avoided if you replace it with a Radice seal which is vented above the waterline.

That's true, of course, and it should be repaired or replaced ASAP, but even if the sterngland is not leaking there are other ways in which water can enter the boat, and having a sump for it to collect in is much preferable to having it slosh around the rest of the boat.

I was once ashore during a thunderstorm in Brittany and I had thoughtlessly left my hatches open as it was a hot day. The amount of rainwater that entered the boat during the associated torrential downpour was astonishing.

 

[pandos]

There is something wrong if your Volvo gland leaks except when burping it after launching. Even this can be avoided if you replace it with a Radice seal which is vented above the waterline.

What he said...your Volvo seal should not leak at all (except for the drop when burping...)
You may need to replace it,

check if it is leaking around the shaft, or from where it fits over the Stern tube. My new one leaked a little there for a period after I fitted it needed to be really tightened up,

 

[goeasy123]

Not sure if it's the same thing as you are talking about but Twisters have a deep well under the forward end of the engine into which any bilge water, or leaks from the engine, drains.

The bilge pump suction strum box(es) are at the bottom of this sump.

There's no pump at the bottom of this sump.

That's true, of course, and it should be repaired or replaced ASAP, but even if the sterngland is not leaking there are other ways in which water can enter the boat, and having a sump for it to collect in is much preferable to having it slosh around the rest of the boat.

The Najad 400 has a deep keel pocket with the inlets for 3 pumps at the bottom of it. This acts as the sump for the whole boat. It's right in front of and below the undrained sump under the engine. If I drill a hole through the bulkhead from the engine sump to the keel sump the standing water problem is solved, but am I creating other problems?

What he said...your Volvo seal should not leak at all (except for the drop when burping...)
You may need to replace it,

check if it is leaking around the shaft, or from where it fits over the Stern tube. My new one leaked a little there for a period after I fitted it needed to be really tightened up,

It did leak when I was away from the boat and filled the sump. The gland was ok, but leaked because something got into the seal from outside the boat and held it open. I checked it wasn't leaking before I left the boat.
I'm replacing it anyway tomorrow. If it leaks again it will fill the sump and overflow into the bilge, across the top of the bulkhead, where there is a pump.

I asked the question on the Najad owners Facebook page. Someone suggested its a requirement to build to meet ISO standards.

 

[pandos]

You could try drilling a hole which is angled upwards towards the front, and ending a few inches up from the base so that oil etc will float on the few inches of water, but excessive water will flow towards the sump pump. (It will act like a gravy separator or an interceptor.. Unique Decorative Vintage Fat and Lean Gravy Fat Separator | Etsy

 

[Plum]

If I drill a hole through the bulkhead from the engine sump to the keel sump the standing water problem is solved, but am I creating other problems?

It is good practice for the area under the engine to be separate from the main bilge sump so that any oil leakage does not get pumped overboard. If you had a major leak it would then be acceptable if that area could overflow to the main sump. In my view, all you need to do is to fix your propshaft seal problem.

Www.solocoastalsailing.co.uk

 

[Poignard]

The Najad 400 has a deep keel pocket with the inlets for 3 pumps at the bottom of it. This acts as the sump for the whole boat. It's right in front of and below the undrained sump under the engine. If I drill a hole through the bulkhead from the engine sump to the keel sump the standing water problem is solved, but am I creating other problems?

Yes you are, because if any oil, diesel or contaminated water gets into the sump under the engine you won't want it going anywhere else.

What I would do is fit a pump suction in that sump and connect it to your main bilge pump via a T-port valve.

Of course in a perfect world, never a drop of anything will get in there but, the world is not perfect . . . .

But regardless of that, you must sort out that leaking gland. I would recommend a packed gland . . . .

 

[Graham376]

The sump under our engine into which our stern gland (if it failed) would drain has no limber hole to the main bilge so I installed a Whale Supersub pump there. Have oil absorbent sausage alongside the pump to avoid any possible engine oil discharge.