Sinking catamaran due to dinghy painter

[geem]

So yesterday a catamaran was reversing off the marina pontoon with his dinghy tied to the stern. The dinghy painter went around one of the props. The wrap ripped the P bracket out leaving a 4" long hole in the bottom. They managed to get the boatyard to lift them up on the travel hoist to stop it sinking. I have never heard ofthas happening before. A rare event?

 

[RupertW]

I don’t think it would have sunk. But a lot of damage anyway.

 

[Chiara’s slave]

I don’t think it would have sunk. But a lot of damage anyway.

No, faorly certain it wouldn’t have sunk. But a boat that can rip itself to bits by means of a rope around a prop, that is surely poor design or construction.

 

[PetiteFleur]

That is why I always use a floating rope on my dinghy - 1/2" Marlow polypropylene rope. Just fitted a new length this year.

 

[RunAgroundHard]

... I have never heard ofthas happening before. A rare event?

Rare I would say.

My experience, not a P bracket but I was doing a 360 degree on the spot and using a lot of RPM to kick the stern round. A line was overboard and went round the prop at high RPM. The engine just stopped. The engine had a frame that it sat on which was then connected to the bearings was twisted and bent out of shape with two of the engine mounts ripped out. So quite a force.

On another occasion I had a 18" warp around a propellor shaft and the warp was like steel it was so tightly wound around the shaft. No exaggeration, it was so densely packed in between the shaft log and propellor hub, there was no softness or displacement, just hard nylon. No P bracket in that case but I can imagine if there was the force required to pack that tight could have damaged GRP.

 

[Bouba]

Because it’s a cat...it probably won’t sink in a port.

 

[ash2020]

We picked up a 2" polypropylene rope going into Oban on a friend's boat. It was an old fish farm anchor rope. It took the RNLI 4 hours to free us. When the boat was hauled out, it was stomach churning to see how close we'd been to sinking. The stern tube had been ripped out and the GRP split apart. The boat was a write off.

 

[lustyd]

That is why I always use a floating rope on my dinghy - 1/2" Marlow polypropylene rope. Just fitted a new length this year.

Just keep in mind that polyprop only lasts a year or two in the sun before turning to dust. It's why fender manufacturers provide polyprop fender lines as they sell more fenders that way!

 

[capnsensible]

I'm wondering why people think a boat won't sink with a 4 inch hole in the bottom......

 

[Bouba]

I'm wondering why people think a boat won't sink with a 4 inch hole in the bottom......

It’s a cat...and in port...so probably just badly list

 

[MontyMariner]

Just keep in mind that polyprop only lasts a year or two in the sun before turning to dust

There must be polyprop and polyprop! I bought some 12mm polyprop from the 'fisherman's co-op' on the quay in Cherbourg, as used on their trawlers, to make up some mooring lines for my fore and aft riverside mooring and used it for about 15 years. I gave it a cursory check evey time I visited the boat and a good close inspection at the start and end of the summer. I replaced it a couple of years ago, only because I thought I should, it's laying around in my shed and still appears to be viable.

 

[geem]

There must be polyprop and polyprop! I bought some 12mm polyprop from the 'fisherman's co-op' on the quay in Cherbourg, as used on their trawlers, to make up some mooring lines for my fore and aft riverside mooring and used it for about 15 years. I gave it a cursory check evey time I visited the boat and a good close inspection at the start and end of the summer. I replaced it a couple of years ago, only because I thought I should, it's laying around in my shed and still appears to be viable.

I use a polypropylene towing bridle for my dinghy. Its several years old and there is no sign of deterioration in the Caribbean sun. I think they do something with the line to stop the UV damage, these days

 

[Graham376]

There must be polyprop and polyprop! I bought some 12mm polyprop from the 'fisherman's co-op' on the quay in Cherbourg, as used on their trawlers, to make up some mooring lines for my fore and aft riverside mooring and used it for about 15 years. I gave it a cursory check evey time I visited the boat and a good close inspection at the start and end of the summer. I replaced it a couple of years ago, only because I thought I should, it's laying around in my shed and still appears to be viable.

There's polypropylene and polysteel (looks the same) which is about 30% stronger with good UV resistance. Our polysteel mooring strops far outlast nylon, in high UV area.

 

[lustyd]

I use a polypropylene towing bridle for my dinghy

Sure it's not polyester, which is UV stable?

 

[geem]

Sure it's not polyester, which is UV stable?

It's the nasty plastic stuff that very coarse. Typical fiahermans line so fairly certain is polypropylene.

 

[Chiara’s slave]

I'm wondering why people think a boat won't sink with a 4 inch hole in the bottom......

Waterproof crash compartments, foam construction, the odd locker that doesn’t fill. No part of our boat would sink, together or broken up.

 

[capnsensible]

Waterproof crash compartments, foam construction, the odd locker that doesn’t fill. No part of our boat would sink, together or broken up.

I don't think that yours is an average yacht.....

Most sink. Seen it. Several times. Some years ago when a boat sank alongside in Haslar Marina due to a faulty hull valve, my opinion that 'his radar is now a sonar' wasn't that well received....

 

[Tranona]

Rare but not out of the ordinary if the conditions are right. Most "common" with twin MOBOs where the props are close together and the rope gets caught on both like a Spanish windlass. Unusual though to pull the P bracket right out but maybe the other end of the rope was attached to something solid and the section of the hull lightly built. Had several photos of damage to stern gear in my rogues gallery when I was involved with rope cutters. Most common were shafts pulled back sometimes taking gearboxes off engines or engines off mounts but bent P brackets common particularly the flimsy jobs used by Sadler and Jeanneau for example.

 

[Baggywrinkle]

A hole can be punched or ripped in any boat, it's just a matter of the force or momentum involved. Luck plays a huge part in that.

Hit a container at 3 knots and only catch it a glancing blow on one of the flat sides and almost any plastic boat will survive.

Get dropped on the corner of a container by a six foot wave and the damage will be substantial.
The probability of both types of encounter are pretty much equal, it's just down to luck.

Here lots of boats impaled on wooden pilings after a storm in the German Ostsee.

Encapsulated keels, skegs, kevlar re-inforcement, steel hulls, watertight compartments ... Murphy's Law will always find a vulnerability and if your number's up, then you're screwed .... as demonstrated by the Titanic where complacency over the perceived invulnerability of the ship cost hundreds their lives.

 

[Chiara’s slave]

When the actual stuff your boat is made from is buoyant it id harder to sink. There might be a ton of flotation in the hull skin and deck, plus 3 unbreached crash boxes and a whole hull. This particular baby isn’t sinking from one hole in 1 hull, murphy or not.