Batten down the hatches

[codprawn]

Originally Posted by Zubenelgenubi

If your D-ring is breaking it must have in inherent design flaw. I assume the D ring proper is not actually breaking but being wrenched from the stem as the hull itself is not sufficiently reinforced where the D-ring is located?
If you need more holding power, in lieu of a samson post why not fit two D rings similar to those used on the SR 4-point bridle arrangement, instead of the D ring being either side of the bows inside the boat have them either side of the bows on the outside of the boat. Essentially a D ring on a stainless steel backing plate for example 5" or 6" square through bolted (Sikaflexed etc) through the hull with a similar backing plate in way of a large "washer" inside the boat.
You can then also use them to secure your boat to your trailer & in a bridle arrangement if you ever need to tow your boat.

Quite the opposite - the hull there is over 1" thick - it's the stainless that fails!!!

Looking at the motion today it is very violent - snubbers on the ropes would help but they are nylon anyway. With the forces involved I really wouldn't want to attach ropes to the console!!!

[JSP]

Originally Posted by codprawn

Quite the opposite - the hull there is over 1" thick - it's the stainless that fails!!!

Looking at the motion today it is very violent - snubbers on the ropes would help but they are nylon anyway. With the forces involved I really wouldn't want to attach ropes to the console!!!

With a well setup spring there wouldn't be that much force.

[chewy]

Originally Posted by JSP

With a well setup spring there wouldn't be that much force.

Or movement.

[Zubenelgenubi]

Well, its obviously the shock load thats doing the damage.
If your boat is tied to a floating pontoon & there is no height difference between boat & pontoon then all lines need to be tight such that the inertia from the bow being kicked by the wind does not cause a sufficient acceleration force to break the D ring. That is why ships lines are bar tight.
Alternatively, the lines need to be long with a catenary in them to dampen the acceleration forces, the catenary can be from long lines, heavy lines or lines with a weight attached to them, a section of chain for example.

[Tim M]

Went out this morning for a bit this morning; was supposed to be picking an outboard up from Bembridge. Was gusting 40 knots at the time. Probably the biggest swells I've ever seen at the mouth of Portsmouth harbour. Didn't stay out too long - turned for home rather quickly. Was more worried about flipping over rather than anything else, and that was in 9m RIB. Fun times

[alystra]

So far I think all the comments and advice are assuming it's the wind that's the problem. From what Codders says, it's the waves that are the trouble. In those circumstances, adding springs will not stop the movement, tight lines will just tear the fittings out of the boat as well as shred the tubes on the pontoons. The pitching and rolling periods of the pontoons and a RIB are never going to be in synch., so sudden shock loads are inevitable.

In heavy weather, i.e when wave tops squirt up through the gaps in the planking, like they do here at times, pontoons are the very worst places for small boats to be. It's much safer, if you have to be afloat, on a swinging mooring.

Those stretchy rubber mooring thingys might help with the problem a bit, but I fear the real answer is to move the boat.

[JSP]

Originally Posted by alystra

So far I think all the comments and advice are assuming it's the wind that's the problem. From what Codders says, it's the waves that are the trouble. In those circumstances, adding springs will not stop the movement, tight lines will just tear the fittings out of the boat as well as shred the tubes on the pontoons. The pitching and rolling periods of the pontoons and a RIB are never going to be in synch., so sudden shock loads are inevitable.

In heavy weather, i.e when wave tops squirt up through the gaps in the planking, like they do here at times, pontoons are the very worst places for small boats to be. It's much safer, if you have to be afloat, on a swinging mooring.

Those stretchy rubber mooring thingys might help with the problem a bit, but I fear the real answer is to move the boat.

Ah I was taking it was in a gated marina, not sure why I jumped to that conclusion.

[chewy]

Originally Posted by JSP

Ah I was taking it was in a gated marina, not sure why I jumped to that conclusion.

Posh git!

[JSP]

Originally Posted by chewy

Posh git!

Here on the west coast the marina's are more refined than your eastcoast crap

[chewy]

Originally Posted by JSP

Here on the west coast the marina's are more refined than your eastcoast crap

£40 a year mate, you can keep your gates.
Refined eh, hows Maryport these days....

[JSP]

Originally Posted by chewy

£40 a year mate, you can keep your gates.
Refined eh, hows Maryport these days....

shut it!
£40 a year, can't be bad. Fleetwood dock has a 8meter min charge. Think it starts off at about £1400 a year. Prestons about the same and in Liverpool you need to be craping gold just to pay the launch fee.

[codprawn]

Originally Posted by alystra

So far I think all the comments and advice are assuming it's the wind that's the problem. From what Codders says, it's the waves that are the trouble. In those circumstances, adding springs will not stop the movement, tight lines will just tear the fittings out of the boat as well as shred the tubes on the pontoons. The pitching and rolling periods of the pontoons and a RIB are never going to be in synch., so sudden shock loads are inevitable.

In heavy weather, i.e when wave tops squirt up through the gaps in the planking, like they do here at times, pontoons are the very worst places for small boats to be. It's much safer, if you have to be afloat, on a swinging mooring.

Those stretchy rubber mooring thingys might help with the problem a bit, but I fear the real answer is to move the boat.

Spot on - its only when the tide rises over the sill the problems start. It doesn't help the finger pontoon is a bit too short either.

Walking on the pontoons is a nightmare - they give sudden lurches quite unlike the motion of a boat.

Before they added the pontoons and the sill it wasn't unheard of for well found boats to sink at their moorings.......

It is such a shame - prob one of the prettiest harbours around with great cruising areas - all for £800 a year.

[Carl]

how does everyone else cope ?

[tonymac]

Originally Posted by JSP

shut it!
£40 a year, can't be bad. Fleetwood dock has a 8meter min charge. Think it starts off at about £1400 a year. Prestons about the same and in Liverpool you need to be craping gold just to pay the launch fee.

I'm amazed about Liverpool! I will say that I did wonder that I didn't see too many ribs on the Mersey anytime I go in on the ferry.

Is it really that expensive to launch in Liverpool?

[alystra]

Originally Posted by codprawn

Spot on - its only when the tide rises over the sill the problems start. It doesn't help the finger pontoon is a bit too short either.

Walking on the pontoons is a nightmare - they give sudden lurches quite unlike the motion of a boat.

Before they added the pontoons and the sill it wasn't unheard of for well found boats to sink at their moorings.......

It is such a shame - prob one of the prettiest harbours around with great cruising areas - all for £800 a year.

Yeah. They've put a floating breakwater here to shelter the pontoons from one wind direction. It's very effective. It's just a long pontoon, but with a continuous float, so the waves are stopped. It's very effective and also provides extra 'row ashore' visitors moorings, so it makes money too. Would the harbour contemplate such a thing? Mind you, I don't know how effective it would be in anything like a decent swell - this one only has just over a half mile fetch.

[JSP]

Originally Posted by tonymac

I'm amazed about Liverpool! I will say that I did wonder that I didn't see too many ribs on the Mersey anytime I go in on the ferry.

Is it really that expensive to launch in Liverpool?

Yeah it is, to use the slip it's £10 to launch, £10 to retrieve and to use the lock it's £6 each way. http://www.liverpoolmarina.com/marina-tariff

There is a slipway at the end of John Lennon Airport but it's for the Sailing clubs use only. That's why I travel 40 miles to fleetwood instead. Plus with my dad living in the dock I get free meals and an extra pare of hands to help launch.
That's until I can get myself a good 4X4 and launch of the beach.

[Carl]

Originally Posted by Tim M

Went out this morning for a bit this morning; was supposed to be picking an outboard up from Bembridge. Was gusting 40 knots at the time. Probably the biggest swells I've ever seen at the mouth of Portsmouth harbour. Didn't stay out too long - turned for home rather quickly. Was more worried about flipping over rather than anything else, and that was in 9m RIB. Fun times

that was sensible for a charter business going out in that weather

[Tim M]

Originally Posted by Carl

that was sensible for a charter business going out in that weather

Wasn't on a charter, me and a friend wanted to go to Bembridge to look at an outboard. Can't see any problem with that. As it turned out, we got of of the harbour, decided it was too rough and went back.

[Carl]

didnt say you were on charter,just not sensible for a charter business to be out playing in a force 11

[Tim M]

Why does the fact I run a charter business have anything to do with it?