Beneteau First 47.7 Bilge leak

[O_salt]

Hi, I have a Beneteau First 47.7, I am getting water into my bilge sump at a daily rate of approximately 4 gallons a day. This is sea water, confirmed by taste and PPM of 1750 via salinity testing.

I have checked the following;
- Stern rudder tube
- Engine compartment, and engine
- Shaft log
- Aft head thru-hulls
- Galley thru-hulls
- speed and depth thru-hulls
- Forward head thru-hulls
- HVAC Thu-hulls, and connections

The grid system in this boat makes it very hard to trace a leak through the bilge as you cannot see alot of the area where water can run.

This water accumulates while we are just sitting.

Anyone have any ideas where the water might be coming from?

Steve

[Jim Cate]

Hate to say it, but the keel bolts and the area of the hull and grid that they penetrate do come to mind. Has the boat ever experienced a hard grounding?

The dreadful photos of the hull of the Cheeki Rafiki (sp?) are imprinted on my memory.

Jim

[Paradoxus]

Does the keel weep when on the dry?

[coopec43]

I think Jim may be on the right track.
http://www.cruisersforum.com/forums/...ing-78631.html

[s/v Jedi]

Instead of the worst case, there are many other possibilities: refrigeration raw water lines, A/C raw water lines, condensers, toilet flush raw water lines etc.

[coopec43]

Originally Posted by s/v Jedi

Instead of the worst case, there are many other possibilities: refrigeration raw water lines, A/C raw water lines, condensers, toilet flush raw water lines etc.

It looks as though he has done an exhaustive check already.

I have checked the following;
- Stern rudder tube
- Engine compartment, and engine
- Shaft log
- Aft head thru-hulls
- Galley thru-hulls
- speed and depth thru-hulls
- Forward head thru-hulls
- HVAC Thu-hulls, and connections

[s/v Moondancer]

1750ppm is not pure sea water!

https://water.usgs.gov/edu/saline.html

[Suijin]

Originally Posted by s/v Moondancer

1750ppm is not pure sea water!

https://water.usgs.gov/edu/saline.html

The point is it’s not rain water or water tank water. It’s coming in from below the water line.

As for the exhaustive check, as Jedi mentions, did you only check the thu hulls or also the lines that run from them? As in closing all the thru hulls and if no leak after a period, opening them one by one to see if there is a hose/fitting leak behind the liner.

The First series, being racers, have an extremely narrow thin fin keel carrying a lot of weight. Depending on the age and history of the boat I’d not be surprised if that were the source of the leak. Dropping the keel on these boats is pretty straightforward as they are shipped with the keel off which is installed by the dealer.

[svHyLyte]

Originally Posted by O_salt

Hi, I have a Beneteau First 47.7, I am getting water into my bilge sump at a daily rate of approximately 4 gallons a day. This is sea water, confirmed by taste and PPM of 1750 via salinity testing.

I have checked the following;
- Stern rudder tube
- Engine compartment, and engine
- Shaft log
- Aft head thru-hulls
- Galley thru-hulls
- speed and depth thru-hulls
- Forward head thru-hulls
- HVAC Thu-hulls, and connections

The grid system in this boat makes it very hard to trace a leak through the bilge as you cannot see alot of the area where water can run.

This water accumulates while we are just sitting.

Anyone have any ideas where the water might be coming from?

Steve

Steve--

Does water continue to accumulate with ALL through-hulls closed?

[Copacabana]

Originally Posted by Jim Cate

Hate to say it, but the keel bolts and the area of the hull and grid that they penetrate do come to mind. Has the boat ever experienced a hard grounding?

The dreadful photos of the hull of the Cheeki Rafiki (sp?) are imprinted on my memory.

Jim

This is good advice- at least examining the keel bolts will put your mind to rest somewhat.

Not to sound alarmist, but another Beneteau First 40.7 recently sank in Brazil when it hit a sandbar. The boat went down in minutes and the owner managed to swim to shore. It seems the keel was ripped out from a fairly soft grounding. I'm not sure if the boat had suffered previous damage, but it does cause concern. If I had a Beneteau First, I'd want to know the keel attachment is OK.

[Copacabana]

Here is a link to an article on the sinking (Google translate should make it readable):

Velejador Elio Somaschini naufraga em Sergipe – Almanáutica

[gmakhs]

I will guess through hole leaking into the grid .
I have a beneteau first 26 same annoying grid , we cut the grid hole bigger than the through hole so we can inspect and for better fit .

[O_salt]

Hi, thanks for all the suggestions, I am going to try closing all the thru-hulls.

I have heard about the keel bolts working lose, I will probably have to haul the boat and see where it is weeping and tighten the keel bolts.

Steve

[gmakhs]

I don't think the keel bolts can leak into the grid , but if you do the re torque make sure to apply the correct tension as BENETEAU states .

[briendaniel]

1. The wheel well on a 47.7 has a drain to a skin fitting. Access is through the starboard side helmsman seat at the transom. This drain can often be blocked by annoying thing such as beer bottle tops or even crud. (A design fault here means if the wheel well fills with water, then water can enter the hull through the top rudder bearing which is just aft of the wheel well.
2. While you are down there, check the rudder post sleeve above the lower bearing.
3. The seal on the prop shaft (from memory it’s a PSS rubber seal) can leak especially if there is corrosion (sometimes hidden) on the prop shaft. Also, this seal can work it’s way forward if only one hose clamp is used around the the shaft - use 2 regardless.
4. If the boat has been grounded sufficiently hard enough you will find hairline cracks around the base of the sub-frame before any compromise around the keel bolts. This is easy to check under the cabin sole amidships port side.
Hope this helps . B