Ladders or what under bridgedeck

[catty]

There was a large "visually challenged'' cat in Aus many years back that had long hydraulically operated leggy things under the wing-deck that were used to slowly walk/drag itself up a beach.

[SurfNRG]

What about posting some pictures to give us a better insight?

[MidLandOne]

Originally Posted by GMac

All I can think of is they are maybe something to do with breaking up waves to stop pounding or similar.

Is that possible and if it is, do they work, anyone know?

It is possible. Many power cats provide cushioning thru' waves by spray making in the tunnel - usually with horizontal chines on the hull. Their tunnels are generally narrower than sailing cats and generally much faster too tho'.

So it is conceivable that the rungs are intended to aerate waves that rise to the bridgedeck in order to reduce slamming. Wouldn't like to comment if it would have much effect tho' if that is their purpose.

Only other thought is as Wotname suggests, despite the sqeals of some . After all is relatively common for multihull designers/owners to want, for reasons of their own, escape hatches should the cat (even cruising ones) invert and I suspect that without something to clip onto in conditions where such an event might take place would be hell of a difficult staying on an upturned hull. But again, and take note multihullers before the red mist passes over your eyes, is a plain guess and would seem pointless to me as I suspect the risk is very small for a big cruising cat.

Bail the owner up with your eye dog and make 'im spill the beans for us, am intrigued .

[Eleven]

18 posts on this already. That's the excuse for knocking on the door.
Storage or wave breaker seem the likeliest BUT -

[cat man do]

Originally Posted by MidLandOne

So it is conceivable that the rungs are intended to aerate waves that rise to the bridgedeck in order to reduce slamming. Wouldn't like to comment if it would have much effect tho' if that is their purpose.

I have always argued that by having large things hanging down to break waves you have provided something to hit the waves and create drag, a ladder would be atrocious.

I had 800mm on the last cat and it very rarely slapped, if I put a big wavecracker or even large stringers in they probably would have.

the new cat has 100mm deep stringers with a moumtain of uni's, but are there for stiffening the panel, not to break waves

Bridgedeck clearance is everything

Only other thought is as Wotname suggests, despite the sqeals of some . After all is relatively common for multihull designers/owners to want, for reasons of their own, escape hatches should the cat (even cruising ones) invert and I suspect that without something to clip onto in conditions where such an event might take place would be hell of a difficult staying on an upturned hull. But again, and take note multihullers before the red mist passes over your eyes, is a plain guess and would seem pointless to me as I suspect the risk is very small for a big cruising cat.

A length of double braid or spectra with figure 8 knots every 10 feet or so is a far cheaper and lighter alternative to clip onto.

Through hull hatches also make great ventilation in the tropics, cool breeze off the water and usually protected from rain

Dave

[Nordic cat]

The escape hatches are actually a CE requirement for offshore boats, I have padeyes, one in each corner of the bridgedeck to clip on to, as well as to attach transvers lines to, if ever my boat gets to its position of infinite stability

[cat man do]

Originally Posted by Nordic cat

The escape hatches are actually a CE requirement for offshore boats,

Different countries different rules especially for non production (are there any for non production?)

Dave

[Eleven]

The French design style of vertical prows and faster boats lead to many (comparatively) up ending. Eventually the French Authorities imposed Escpae Hatches which, being the United!!! States of Eutrope means they all have to have them.
Prouts were not known for tipping, EVER. BB are like minded Cruising Boats related to Prouts.
When Brits make racers they can surely tip over, but the cruisers are much more forgiving with flared and bouyant bows and rear set masts giving a huge lifting force from the angle forestay / fore sail.
Try standing a person on each bow of a French Multi under way. If they stay there you've got a good boat and this design issue has been addressed. Try it on 'Expo try a boat' days. Very interesting results!!! including lack of handholds on some, tramp issues, safe foredeck working such as chute deployment and bridle rigging.

[Nordic cat]

Originally Posted by cat man do

Different countries different rules especially for non production (are there any for non production?)

Dave

No, for any multi going over a certain distance from shore, they have different categories, Category A is for more than 200 miles offshore. B is 40 miles I think. I can find out if you like??

Racing boats don't need to adhere to these rules, they have a different set, but I think they also require the escape hatches.

In fact we are starting to see them in the transoms of big monos now, but I don't know if it is a CE requirement. Could be, based on distance from say an aft cabin to the main hatch. Maybe someone clued up can clarify?

Alan

[cat man do]

All I could find for Australia is a reference in some racing rules

Multihulls

• 3.06.5 Boats less than 12m LOA, with an age date of 7/2006 will require escape hatches to the same specifications as Multihulls over 12m LOA.

Changes in the YA Special Regulations 2005 - 2008



That was in the 2 pages on Google using these search words

escape hatches multihulls Australia rules regulations

Dave

[MidLandOne]

In response to a few comments -

The ISAF Offshore Special Regulations require clipping points and handholds under the bridgedeck of cats and on the centre hull of tri's for in case of inversion. While those rules are for race boats they are widely used as guidance for cruising vessels and, for example, NZ requires that NZ vessels embarking on foreign voyages comply with them (with a bit of latitude at the inspector's discretion). I don't know if the inspectors allow ropes as meeting this requirement - in my experience they are wary of fibre ropes meeting similar requirements eg lifelines must be stainless steel.

So if the boat GMac refers to is a NZ flagged vessel seems is a reasonable possibility the rungs are to fulfil that compliance requirement, and may still be so if a foreign flagged vessel.

[MidLandOne]

Originally Posted by Nordic cat

In fact we are starting to see them in the transoms of big monos now, but I don't know if it is a CE requirement. Could be, based on distance from say an aft cabin to the main hatch. Maybe someone clued up can clarify?

I have only seen them in the transoms of big wide beamed "ironing board" type race monos, not any cruising monos (but that is not to say they are not to be found - can find almost anything somewhere, someplace though, no matter how nonsensical ).

I don't know about CE but as far as I know ISAF Offshore Special Regulations don't require them but I am on the boat and only have the 2006-2007 rule here (they make no mention of them for monos). May be mentioned in the current rule.

But, there is a general good sense design requirement (probably also said in ABYC and CE but I don't have copies with me) that there be alternative means of escape from all compartments, that in case of fire. In common sized monos that normally only implicates the forward cabin(s), and for centre cockpit boats the aft cabin; all solved by a deck hatch - aft cabins in an aft cockpit boat regarded as near enough to the companionway and also obviously not possible to have a big hatch in every cabin.

CE may have something about escape hatches in case of inversion of monos but I suspect not as the run of the mill euro production boats don't seem to have them.

[GMac]

I popped down to the boat and it's more 60-65ft, alloy and while in need of a nice tidy up, she is quite a sexy beast. She's also done a lot of miles looking at her. Strangley very blunt bows which I thought was interesting.

No body home but I sussed the best I could under her. She does have lots of longitudinal stringers right across the bottom of the bridge deck. Alloy T section ones about 3inches deep each.

It appears that under each side of the bridge deck just inside each hull, the floor has been lowered, for extra headroom or something, about 6-8 inches deep and about 3ft wide. Under there is stringers just like the rest but also 4 stringers which are closer to 8-9 inches deep. Across the bottom of those is some 2" strips running beam wise. I'm trying to use the A word mean sideways but can't get it close enough for the spell checker to make it readable

That lower set of stringers and the sideways bits are what I saw as the 'ladder' things.

I'm now not so sure they are a wave break thing and might just be extra stiffening. Just does seem a bit weird really. Maybe a 'Under roof rack' for windsurfer storage crossed my mind but as this thing has football field sized decks they aren't short of space up there. Just quite figure it out.

I would have taken a photo if I had remembered my camera and if anyone knows where I left my phone on Monday, I could use that next time

No sign of any escape hatches but it was a bit tricky to get a real good look by the way she is parked.

I will continue to see if I can catch up with the owner.

FYI - At rest in the marina the middle of the bridgedeck is only 2ft 6 - 3ft max maybe above the water and less out to the sides. It is lower than most I've seen but she does have quite full hulls so maybe she just sits up and rocks along. I'd say she would be a fantastic boat to cruise in and have quick passage times.

[MidLandOne]

The "A word" = "Athwartships" maybe?

If there are longitudinals 8-9 inches deep with the 2'' ones athwartships across their bottom edges then it could be that the 2" ones are just there to stop the bottoms of the deep longitudinals tipping when under bending from the load on the deck they are supporting.

Not sure why there would be such a load there requiring all that structure but not elsewhere across the bottom plating of the bridgedeck though.

John

[GMac]

Originally Posted by MidLandOne

The "A word" = "Athwartships" maybe?

That's the bugger. I wasn't even close

[quoteNot sure why there would be such a load there requiring all that structure but not elsewhere across the bottom plating of the bridgedeck though.[/quote]

Exactly my thinking.