Cabin cruiser bilge, to vent or not to vent?

[Dockeroo]

Hi, im completely new to boating but bought a tired 1976 grp canal cabin cruiser a year ago thats moored in the water, just started working on her. Im very handy and can do it all myself, but has been a big learning on curve how boats work.

 

I've found myself directed to these forums allot so thought id make an account.

 

So the bilge in my cruiser (outboard engine) gets damp (it's actually leaking a small amount, but Im I'm the process of diagnosing this) should I vent it through the floor somewhere Or? Or put the floor on top so it's pretty much sealed?

 

I wanted inside the cabin to be nice and dry with no smells, so was going to seal the floor as much as I can, but thinking about it... not sure, haven't been able to find any answeres online, hoping someone can help.

 

Thanks!

Also.. it had about 100-120kg of sand bags right at the front of the boat, which made it sit leaning forwards quite allot leaving un-level, ive taken these out and is now sitting nice as pictured, anyone know why they were there?

 

Edited April 22, 2022 by magpie patrick
At the request of the poster

[Quattrodave]

Most boats have water in the bilge, be it river water, condensation or a roof / window / hatch rain water leak... how much water are we talking about?

Edited April 19, 2022 by Quattrodave

[Dockeroo]

Today was the first time I've been able to check, as a few days ago I hoovered about 12 5L hoovers full of water from the front and rear bilge (Bilge pumps haven't been on for over 2 years)

 

And today it had about a pint or 2 in the bilge, with no rain.

 

When I first bought it, it was raining lots, and the water went above the floor line, but disappeared ever since to below the floor (the bottom of the Bilge is about 5 inches deep below the floor)

 

Today I cleaned all inside the cabin, so there was quite bit of water from cleaning, but I noticed a tiny stream of water coming from the middle left side of the Hull (it goes under the seating wood which I don't want to remove if possible), its either going through the Hull, or is draining from the deck near the windows?

Edited April 19, 2022 by Dockeroo

[Quattrodave]

Hmmm first job fit a bilge pump I thinks... second, find if / where the leak is coming from... it might just be your boat drying out from rain and cleaning water....

Edited April 19, 2022 by Quattrodave

[Mad Harold]

The favourite places for leaks on a grp boat are, the windows, either the frame to cabin seal, or the glass to frame seal.Next are hull fittings, mooring cleats, fender hangers, pulpit rail fittings etc.

The rubbing strip is another source of leaks, in that the screws holding it on are either missing or the holes have become enlarged over the years and the screws are now a push fit.

A leak through the hull is rare, but possible if the hull has had a bang, and been badly repaired,or has suffered some de lamination and again has been repaired without being dried out first.

The cabin bilge will usually be damp, and pong a bit mouldy, but should not be wet.You can usually fit a vent to help it breathe.

Little grp boats are usually a bit wayward at canal speeds as they are light and shallow draught, and some people add ballast forward as this is (supposedly) to improve directional stability, although I am not convinced.

[Dockeroo]

22 minutes ago, Mad Harold said:

The favourite places for leaks on a grp boat are, the windows, either the frame to cabin seal, or the glass to frame seal.Next are hull fittings, mooring cleats, fender hangers, pulpit rail fittings etc.

The rubbing strip is another source of leaks, in that the screws holding it on are either missing or the holes have become enlarged over the years and the screws are now a push fit.

A leak through the hull is rare, but possible if the hull has had a bang, and been badly repaired,or has suffered some de lamination and again has been repaired without being dried out first.

The cabin bilge will usually be damp, and pong a bit mouldy, but should not be wet.You can usually fit a vent to help it breathe.

Little grp boats are usually a bit wayward at canal speeds as they are light and shallow draught, and some people add ballast forward as this is (supposedly) to improve directional stability, although I am not convinced.

Thanks much appreciated, very informative!

 

Luckily I'm changing the rub rail and all cleats and fittings so will make sure is all sealed properly.

 

What would you use to fill the old rub rail holes? (As I'll drill in new holes for the new one) I've got sikaflex sealant (or whatever it's called 😅) or should a use an actual filler?

 

I think it sounds ideal to pit a small vent in the floor.  

 

Thanks for the replies 

[Balloon]

On 19/04/2022 at 22:30, Dockeroo said:

 

 

Also.. it had about 100-120kg of sand bags right at the front of the boat, which made it sit leaning forwards quite allot leaving un-level, ive taken these out and is now sitting nice as pictured, anyone know why they were there?

I don’t know but I wonder, if it sits nice and level like that with the boat unoccupied, whether the 100kg of sand bags were intended to balance the effect of a 100kg person at the helm? How does she sit in the water with someone at the helm? Will obviously depend on their size…

 

additionally, regarding leaks, you’ve already had great advice and I’m sure this will solve your problems but if you are left with pesky small leaks that you can’t seem to diagnose, I was recommended a while back”captain tolley’s creeping crack cure” which, in my experience, is flawless at finding and sealing small leaks. It flows and behaves like water so finds its way into small cracks but then sets. 

Edited April 22, 2022 by magpie patrick

[BEngo]

Definitely vent the bilge.  Smelly moulds and algae cannot grow if it's not damp and a good through flow of air will dry things out.

Also fit an inspection hatch, toward the back, so you can see how things are under the floor.

 

If you think you have a hill leak, fluorescein dye (from Screwfix)  dribbled around the outside of the boat will soon show in inside if there is a leak.

 

N

[Barneyp]

If you had to remove 12.5 litres of water in the past few days, and from the sound of it there has regularly been large amounts of water in the bilge, it is likely that the wood that supports the deck and possibly the deck boards themselves have soaked up water. This water will gradually drain out if the wood is no longer sitting in water.

If you install automatic bilge pumps,or regularly (every day or 2) use your wet vac to empty the bilge it may still take weeks or maybe even months for the wood to fully dry out.

Check all the wood in the bilge, especially the bulkhead that divides the 2 bilges, for rot.

Not sure what you mean by having the floor sealed, you need to be able to easily lift the deck boards so you can check the bilge, and there is always likely to be some water that finds it way down there so its good to have airflow to help it dry out.

[Tonka]

How old is the Grp. Could it have osmosis

[David Mack]

3 hours ago, Balloon said:

I don’t know but I wonder, if it sits nice and level like that with the boat unoccupied, whether the 100kg of sand bags were intended to balance the effect of a 100kg person at the helm? 

Or a larger and heavier outboard motor than is now fitted?

[TheBiscuits]

11 hours ago, Mad Harold said:

Little grp boats are usually a bit wayward at canal speeds as they are light and shallow draught, and some people add ballast forward as this is (supposedly) to improve directional stability, although I am not convinced.

 

Depends entirely on hull profile and trim.

 

The standard Nauticus 27 was almost unsteerable at canal speed.  Cutting a hatch in the apex of the vee berth and adding ~200kg of ballast as far forward as possible made it track nicely.

 

I thought it sounded a lot but getting three people to sit on the bow while underway convinced me it was about the correct weight.

 

With a different hull shape it might not make as much difference.

[Mad Harold]

2 hours ago, TheBiscuits said:

 

Depends entirely on hull profile and trim.

 

The standard Nauticus 27 was almost unsteerable at canal speed.  Cutting a hatch in the apex of the vee berth and adding ~200kg of ballast as far forward as possible made it track nicely.

 

I thought it sounded a lot but getting three people to sit on the bow while underway convinced me it was about the correct weight.

 

With a different hull shape it might not make as much difference.

A lot of grp cruisers have a semi planing hull, possibly the makers are trying to appeal to as wide a section of boaters as possible.

This type of hull is fairly directionally stable at speed, but less so at 4mph.

The displacement hull is more directionally stable at low speeds.

As an aside I thought the Nauticus 27 had a displacement hull, but I could be wrong.

With three people on the bow, I hope you didn't have to do an emergency stop!  😃

[TheBiscuits]

12 minutes ago, Mad Harold said:

As an aside I thought the Nauticus 27 had a displacement hull, but I could be wrong.

With three people on the bow, I hope you didn't have to do an emergency stop!  😃

 

Nah, it's a semi-displacement with a solid 8x5 inch keel. 

 

The ballast minions were holding on to the pulpit rail and told to keep their legs on the deck, so they survived!

[Dockeroo]

On 20/04/2022 at 08:43, Barneyp said:

If you had to remove 12.5 litres of water in the past few days, and from the sound of it there has regularly been large amounts of water in the bilge, it is likely that the wood that supports the deck and possibly the deck boards themselves have soaked up water. This water will gradually drain out if the wood is no longer sitting in water.

If you install automatic bilge pumps,or regularly (every day or 2) use your wet vac to empty the bilge it may still take weeks or maybe even months for the wood to fully dry out.

Check all the wood in the bilge, especially the bulkhead that divides the 2 bilges, for rot.

Not sure what you mean by having the floor sealed, you need to be able to easily lift the deck boards so you can check the bilge, and there is always likely to be some water that finds it way down there so its good to have airflow to help it dry out.

Good news I went back after no rain and a sunny day and the Bilge was completely dry, so it must have been from washing it/ rain from a few days ago.

 

Most of the fittings on top are loose and no longer sealed, so am replacing all of them for new anyway.

 

Thanks for the input everyone

On 20/04/2022 at 14:14, Mad Harold said:

A lot of grp cruisers have a semi planing hull, possibly the makers are trying to appeal to as wide a section of boaters as possible.

This type of hull is fairly directionally stable at speed, but less so at 4mph.

The displacement hull is more directionally stable at low speeds.

As an aside I thought the Nauticus 27 had a displacement hull, but I could be wrong.

With three people on the bow, I hope you didn't have to do an emergency stop!  😃

This sounds like the reason it was there, as the hull hasn't got much of the front "V" actually in the water.

 

Is there some type of fin or something I could attatch to the front? I'm getting it out of the water to sand and repaint the hull. This boat will be on canals only while I have it, if I put any weight at the front it sits leaning too far forward really.

[Mad Harold]

2 hours ago, Dockeroo said:

Good news I went back after no rain and a sunny day and the Bilge was completely dry, so it must have been from washing it/ rain from a few days ago.

 

Most of the fittings on top are loose and no longer sealed, so am replacing all of them for new anyway.

 

Thanks for the input everyone

This sounds like the reason it was there, as the hull hasn't got much of the front "V" actually in the water.

 

Is there some type of fin or something I could attatch to the front? I'm getting it out of the water to sand and repaint the hull. This boat will be on canals only while I have it, if I put any weight at the front it sits leaning too far forward really.

Not really practical to fit a fin fwd. I have heard of a grp boat that had a bit of keel glassed in at the stern, but I think that would be a load of hassle.

When I had my first grp cruiser the advice I got from an old 'lag grp man' was "practice,practice, practice"

After a few hours you will get to know your boat's little tricks.

[Dockeroo]

19 minutes ago, Mad Harold said:

Not really practical to fit a fin fwd. I have heard of a grp boat that had a bit of keel glassed in at the stern, but I think that would be a load of hassle.

When I had my first grp cruiser the advice I got from an old 'lag grp man' was "practice,practice, practice"

After a few hours you will get to know your boat's little tricks.

I see, having never driven a boat before I am a bit anxious I'll crash it 😅 but I'm sure I'll work it out like you say.

[Barneyp]

4 hours ago, Dockeroo said:

Good news I went back after no rain and a sunny day and the Bilge was completely dry, so it must have been from washing it/ rain from a few days ago.

 

Most of the fittings on top are loose and no longer sealed, so am replacing all of them for new anyway.

 

Thanks for the input everyone

This sounds like the reason it was there, as the hull hasn't got much of the front "V" actually in the water.

 

Is there some type of fin or something I could attatch to the front? I'm getting it out of the water to sand and repaint the hull. This boat will be on canals only while I have it, if I put any weight at the front it sits leaning too far forward really.

If you fitted a fin or keel at the front it would need to be very strong and very well attached, and if it was even slightly out of alignment or just caught a piece of floating litter or debris it would  throw you of course.

I think Mad Harold is right, it all comes down to practice.

Do you know what make your boat is, there is likely to be an owners group/website/Facebook where you could get more specific advice.

[Dockeroo]

11 minutes ago, Barneyp said:

If you fitted a fin or keel at the front it would need to be very strong and very well attached, and if it was even slightly out of alignment or just caught a piece of floating litter or debris it would  throw you of course.

I think Mad Harold is right, it all comes down to practice.

Do you know what make your boat is, there is likely to be an owners group/website/Facebook where you could get more specific advice.

This was a struggle when I was working out what I wanted to do with it/ and the layout.

I searched Google but couldn't find a boat similar, it's got a front hatch and a roof instead of a full bimini

 

It's a Loftus Bennet 1978 cabin cruiser. I would like to see the same boat that someone else has just to see another example.

[Alan de Enfield]

3 minutes ago, Dockeroo said:

It's a Loftus Bennet 1978 cabin cruiser. I would like to see the same boat that someone else has just to see another example.

 

 

1978 Loftus Bennert 16ft

 

1978 Loftus Bennet 19ft

 

 

Loftus Bennet 17ft

 

[Bacchus]

I am assuming it's an outboard - adding a vestigial rudder can help tremendously with slow speed manoeuvring and directional stability on a small GRP cruiser

 

You can buy kits, but I can't think it would be that difficult to fabricate - search "add a rudder" and you'll find loads of images.

[Dockeroo]

29 minutes ago, Alan de Enfield said:

 

 

1978 Loftus Bennert 16ft

 

1978 Loftus Bennet 19ft

 

 

Loftus Bennet 17ft

 

 

How many models did they make that year 😂 here's mine, can't find another example

 

Edited April 22, 2022 by Dockeroo

[Mad Harold]

15 hours ago, Dockeroo said:

 

How many models did they make that year 😂 here's mine, can't find another example

 

I suggest Googling The Norman Owners Forum and joining. 

If you post a few pictures of your boat, and ask what it is, there are some long established members who love to try to identify lesser known boats.

Not knocking CWF, but the members on Norman Owners are mostly more au fait with grp outboard powered boats.