Sizing mooring lines correctly?

[Boathook]

My 'berth' mooring lines are 18mm 3 strand nylon - I think. Might even be 22mm. What ever size, over engineered and there are 4 of them plus a spring of around 14mm. All this for my 5 ton cruising Cat. When away I use either 12 or 14mm 'nylon'. If I had to leave my boat elsewhere I would possibly double up lines for peace of mind, but so far haven't needed to.

 

[Stemar]

I see a lot of boats attached to a pontoon with short lines, especially at the stern, where you may only have a couple of feet between the cleat on board and the one on the pontoon. It's even worse on a cat, where both bow and stern lines are sometimes this short. This always scares me a little, because the short line gives so little elasticity, the shock loads must be enormous.

On our old boat, I'd pull the stern in fairly tight, but go from the aft outboard cleat ashore, and allow the bow to sit away from the pontoon to give a bit more length. On my current cat, the breast lines are always from the outboard cleat fore and aft for the same reason. It's also more pleasant aboard if there's a bit of swell or wake from passing ships.

 

[dunedin]

I see a lot of boats attached to a pontoon with short lines, especially at the stern, where you may only have a couple of feet between the cleat on board and the one on the pontoon. It's even worse on a cat, where both bow and stern lines are sometimes this short. This always scares me a little, because the short line gives so little elasticity, the shock loads must be enormous.

On our old boat, I'd pull the stern in fairly tight, but go from the aft outboard cleat ashore, and allow the bow to sit away from the pontoon to give a bit more length. On my current cat, the breast lines are always from the outboard cleat fore and aft for the same reason. It's also more pleasant aboard if there's a bit of swell or wake from passing ships.

Often don’t have much options with finger pontoons, which typically barely reach the stern cleat, if that. Certainly can’t pot a rope from the outboard cleat in these circumstances. And if leave stern line too loose in narrow berths, boat will blow off a LONG way in. F9+, which may cause problems with neighbours.
We have a short stern rope, with rubber snubber on. But to prevent going too far out in gales, we also have a second rope from the far side of the pontoon (tied under our neighbour’s ropes so they can go in and out) which gives a slightly better angle (albeit not ideal for them arriving onto pontoon if windy, but fine for winter)

 

[Refueler]

Finger pontoons are always a problem ... even for small boats like mine at 25ft.

Its part of the reason I am a believer in 2 lines in the fore and aft positions. My boat also has midships cleats - so they are used as well.

My home pontoon is 6m x 4m and I still have the overhang problem !!

 

[Stemar]

Point taken re short finger pontoons, you may not have a choice, but I almost never use them. I'm thinking more of the Hardway SC pontoon, a few 100 yards long, and regularly subject to wake from passing boats who may remember the 10kt speed limit, but forget about the no wake bit.

 

[geem]

My Mates B31 went walk about when his spring snubber decided enough was enough ....

Like me - he now no longer uses snubbers.

The trick is to use the lines better. Instead of single line at positions - I prefer two lines which can be of reduced diameter but total gives better solution. If one does part - at least other is there to hold.

I think many of us 'budget' conscious boaters often take replaced halyards and divide up into useful lines such as use for berth mooring lines. Even a couple of 10mm would be IMHO better than a single 16 .. 18mm line.
Easy to handle a single line coming in / departing ... once alongside - second line added as security.

My 4 ton boat sits on such lines .......

My very substantial springs (19t boat) have bypass chains around the springs. If the spring was to fail the line would still be connected albeit with no snubbing. We use 24mm lines as our back up lines. These are set slightly longer than the normal mooring line lengths so they don't start to take any load until the main lines are stretching fully. They are out storm lines. They normally only get deployed in a winter marina berth.

 

[dunedin]

My Mates B31 went walk about when his spring snubber decided enough was enough ....

Like me - he now no longer uses snubbers.

The trick is to use the lines better. Instead of single line at positions - I prefer two lines which can be of reduced diameter but total gives better solution. If one does part - at least other is there to hold.

Sorry but boats that are properly tied up don’t go walk about due to rubber snubbers breaking.
1) Decent ones are very durable - we have been through a lot of severe storms
2) Properly designed ones the rope would still hold if the snubber did snap - as passes through so just a bit looser
3) Should always have secondary ropes ready if one breaks
Have heard of poor boat owners where the pontoon has broken free or similar, which is very difficult to guard against, but should always stay attached to pontoon and with the above a rubber snubber is not a failure issue

 

[Refueler]

Sorry but boats that are properly tied up don’t go walk about due to rubber snubbers breaking.
1) Decent ones are very durable - we have been through a lot of severe storms
2) Properly designed ones the rope would still hold if the snubber did snap - as passes through so just a bit looser
3) Should always have secondary ropes ready if one breaks
Have heard of poor boat owners where the pontoon has broken free or similar, which is very difficult to guard against, but should always stay attached to pontoon and with the above a rubber snubber is not a failure issue

Did I say RUBBER snubber ???? I said SPRING snubber .... you know those metal coil type ....

If you put a secondary line with those - it would soon chafe ......

The mooring in question is a Baltic style bows to pontoon and stern line to buoy. When the spring snubber parted - his boat ended up hanging on one bow line and the bouyed stern line ... laying alongside next boat ...

 

[Refueler]

My very substantial springs (19t boat) have bypass chains around the springs. If the spring was to fail the line would still be connected albeit with no snubbing. We use 24mm lines as our back up lines. These are set slightly longer than the normal mooring line lengths so they don't start to take any load until the main lines are stretching fully. They are out storm lines. They normally only get deployed in a winter marina berth.

I did mention to him that I did not think it was a good item ... turned out I was not wrong.

 

[geem]

I did mention to him that I did not think it was a good item ... turned out I was not wrong.

How? We have never broken a spring but the backup is there should it ever happen