How safely can large catamarans dry out?

[haydude]

Coming down on a rock is a legitimate concern, but If a catamaran needed level support across a perfectly flat beach, I'd worry about its ability to withstand waves at sea.

Pete

+1

I believe that choppy waters or 2m+ waves would put the multihulls to much more stress than a slightly uneven beach and thus, if you are concerned about the latter what about the sea worthiness?

 

[bbg]

It'd be unfortunate, never to benefit from a cat's ability to sit comfortably upright on any clean bottom, simply because one hadn't equipped basic systems to cope between tides.

The nice thing is that cats have the ability to sit comfortably upright even when they are in the water.

Do you know of any bilge keelers that have been equipped with these "basic systems to cope between tides"?

 

[Felixcat]

I built a Woods plywood cat. Woods recommends supporting the boat at three corners and swinging on the other to check deflection, at a certain point in the build. I think he comments that in any size of sea the stresses will be rather more than caused by this. I could not detect any.
When I came to fit the bridgedeck cabin to the fore beam I found a misalignment of about 8 mm. at one side. (It was already fixed to the afterbeam and cockpit.) Perhaps I'm not the most skilled builder. Nearby was steel monohull in build and the future ballast was ready. This was a pile of stone offcuts and waste from a monumental mason's yard. I borrowed this to try to force the cabin into alignment but could only reduce it to about 4 mm. Even in this unfinished state the boat was impressively rigid.
As several commenters have said, forces at sea will exceed anything uneven grounding could inflict.

 

[Greenheart]

...Even in this unfinished state the boat was impressively rigid. As several commenters have said, forces at sea will exceed anything uneven grounding could inflict.

Point well taken, I thank you.

Do you know of any bilge keelers that have been equipped with these "basic systems to cope between tides"?

I hadn't enquired. Evidently I'm in the dark about this small point, because I still don't understand...

...considering periods spent drying out won't be longer than 12 hours, (potentially a very long time for bowel and bladder to wait!) I'm surprised if owners of any large boats which can dry out, regard use of the toilet at such times as something not worth preparing for...it's only 12 hours, so no vast additional flushing/holding tankage would be needed to enable use...but wilfully restricting all use of the loo when drying out, just to obviate extra tankage, seems a tightfisted, comfortless approach to cruising...

...especially when ability to dry-out isn't that widely-held and ought to add plenty to the pleasure of ownership. It scarcely seems worth having, if the boat descends through several degrees of comfort whenever she's not actually floating. I really wouldn't make this point if it didn't appear (to me) so easily corrected.

 

[bbg]

Point well taken, I thank you.

I hadn't enquired. Evidently I'm in the dark about this small point, because I still don't understand...

...considering periods spent drying out won't be longer than 12 hours, (potentially a very long time for bowel and bladder to wait!) I'm surprised if owners of any large boats which can dry out, regard use of the toilet at such times as something not worth preparing for...it's only 12 hours, so no vast additional flushing/holding tankage would be needed to enable use...but wilfully restricting all use of the loo when drying out, just to obviate extra tankage, seems a tightfisted, comfortless approach to cruising...

...especially when ability to dry-out isn't that widely-held and ought to add plenty to the pleasure of ownership. It scarcely seems worth having, if the boat descends through several degrees of comfort whenever she's not actually floating. I really wouldn't make this point if it didn't appear (to me) so easily corrected.

There is no difference between large boats and small boats in terms of what you see as inconvenience. If it is inconvenient not to have a loo on a large boat, why would it be any less inconvenient on a smaller boat?

I rather suspect that there are very very few owners of large cats that see drying out as a typical thing to do. To put it in your words, the ability to dry out probably does not add much, if anything, to the pleasure of ownership for most owners. It is - for most owners - something they never do and never will do.

So I rather suspect that boats are not prepared for drying out because it is something that, for most boats, will never happen. If someone intended to dry out regularly, they might prepare the boat for it.

 

[Greenheart]

I was thinking by "large", anything over 35ft...so not necessarily full-time world or Caribbean cruisers - I meant UK-maintained...and small enough to creek-crawl comfortably if the occasion demands, assuming her structure allows. Whereupon, I'd imagine any doubt that the vessel's basic comforts - like lavatories - are usable, might be a ridiculous embarrassment, and so easily solved as not to be worth taking a chance over. So I'm surprised if the question of flushing water capacity is routinely overlooked at the design stage.

I wasn't suggesting people need the loo less in smaller boats - but finding space for an extra few flushes of water must be less trouble aboard a larger vessel than a smaller one, so I wouldn't have been surprised if smaller boats are typically less able to flush while dried out.

 

[bbg]

So I'm surprised if the question of flushing water capacity is routinely overlooked at the design stage.

Large catamarans are not designed for the use to which you refer. That potential market must be a few tens of people and would require a significant increase in cost, so there should be no surprise that they are not designed for it.

If you look at the worldwide population of 35-45 foot production catamarans, there must be hundreds if not thousands around the world. How many of those are in the UK? And how many of those would EVER be put to the use to which you refer, let alone be used in that way regularly?

I suspect you are talking about one tenth of one percent of the population of boats in that category. And all your points about flushing apply equally well to monohulls that can take the ground, so I don't know why you restrict your criticism (or astonishment) to catamarans. In fact, since most boats that do dry out regularly are smaller monohulls, it seems sensible that appropriate systems would be more useful on such vessels even if the associated compromises in terms of space etc were - relatively speaking - greater.

 

[TSB240]

I suddenly have an image of Dan trading his Osprey in for an old Dart 18 suitably kitted out for Creek crawling.

Overnight tenting on the trampoline and fitted with a loo seat bolted to the front cross beam for his comfort and relief after a long passage, a decent session in the pub or a hot curry night!

Wouldn't need any transom flaps for sure!

Dried out plenty of times never had issues with flushing in the middle of the night as long as the tide came back in well before my morning swim!

 

[Adonnante]

I carry a Porta Potti for the odd emergency!

 

[stephen_h]

A bucket of water poured into the loo and pumped to a holding tank would suffice.
Drying out is one of the great pleasures of owning a cat and shouldn't be a problem
for any cruising cat.

 

[Greenheart]

If you look at the worldwide population of 35-45 foot production catamarans, there must be hundreds if not thousands around the world. How many of those are in the UK? And how many of those would EVER be put to the use to which you refer, let alone be used in that way regularly?

More than a tenth of one percent, if we may assume that not everybody who ever dries out, has responded here. Quite sufficient to make the question worth asking.

...all your points about flushing apply equally well to monohulls that can take the ground, so I don't know why you restrict your criticism (or astonishment) to catamarans.

You brought monohulls into this thread, bbg, not me...the issue of whether on-board conveniences are usable when dried out, wasn't any part of my original question. I only wanted to know if bigger multis could dry out.

I certainly don't single-out multihulls as objects of my surprise, if indeed most bilge-keelers and lifting-keelers are also unable to flush their loos when dried out. To my mind (far from your offshore outlook, I accept) drying out is a fine thing to be able to do - but in the almost-complete absence of bilge keel monohulls over about 35ft, I wondered whether bigger cats are imperiled when they dry out. Apparently, many well-built cats are perfectly able to, and according to lots of contributors here, it's not unusual to do so.

Drying out is one of the great pleasures of owning a cat and shouldn't be a problem for any cruising cat.

Thank you, Mr H. That's exactly what I hoped to hear. :encouragement:

 

[bbg]

I certainly don't single-out multihulls as objects of my surprise, if indeed most bilge-keelers and lifting-keelers are also unable to flush their loos when dried out. To my mind (far from your offshore outlook, I accept) drying out is a fine thing to be able to do - but in the almost-complete absence of bilge keel monohulls over about 35ft, I wondered whether bigger cats are imperiled when they dry out. Apparently, many well-built cats are perfectly able to, and according to lots of contributors here, it's not unusual to do so.

I guess this is what I don't understand. Why do you limit your view to boats over 35 feet? There are almost certainly more "man-hours" spent dried-out on boats below 35 feet. Probably on boats below 30 feet. It is just as inconvenient for those people not to use the heads, so (since they are spending more time dried out) perhaps they should be more keen to sacrifice a little space to allow them to do so?

Or perhaps - since the boat has dried out - it is just easier to walk ashore and find a loo?

 

[Greenheart]

Ah, I see, I think. The reason behind the thread was that I was wondering how large a yacht can be, and still make use of shallow draft for visiting drying harbours and beaches. I don't much like the interiors of most centreboarders, and there really aren't many (any?) bilge keelers over about 35ft...

...so, I asked myself, what other kind of yachts, above that size, might be able to dry out unsupported? The only answer I thought of, was catamarans...

...and I was just wanting to know if they are able to. That was my only original ponder.

On the wholly secondary question of whether boats which dry out, ought to be able to flush their loos and contain their waste when dried-out, I'd agree it has to be each owner's choice, depending on how often he anticipates needing that ability, and whether he wants to lay out the cost of the system/additional tankage it will require...

...and I can see that the cost of acquiring that ability may well be about the same aboard a 24ft yacht, as on a 48fter...yet it'd possibly be a prohibitive proportion of the smaller yacht's total value. A pity, since the smaller yacht is far more likely to have need of it, being better suited to drying out.

I've admitted how unfamiliar I am with yacht lavatories, and their plumbing. I can only say (however odd or unusual it may make me sound) that when I have a yacht which can dry out, I shall do so as often as possible, in scenic and remote places which I'd certainly never want to pollute. So, rare as my choice may be, I'll be supplementing the tankage in order that the loo continues to flush into a capacious holding tank, even in those lovely surroundings.

I remain a bit surprised, if most other people who also enjoy the freedom to dry out in beautiful tidal areas, are perfectly content not to use their loo for the long period until the tide returns. Because to me, it doesn't seem like a lot more to expect. Oh well.

 

[bbg]

I can only say (however odd or unusual it may make me sound) that when I have a yacht which can dry out, I shall do so as often as possible, in scenic and remote places which I'd certainly never want to pollute. So, rare as my choice may be, I'll be supplementing the tankage in order that the loo continues to flush into a capacious holding tank, even in those lovely surroundings.

I don't think it makes you sound odd or unusual at all. It sounds a wonderful way to cruise, whether you are the only one doing it or whether you are one of thousands doing the same thing. Not something that appeals to me, but I can see that it would appeal to others, and to each their own. Enjoy.

 

[Greenheart]

...to each their own. Enjoy.

Cheers to that.

It isn't that I don't want to sail offshore - but my own experience is predominantly coastal, and my pleasure is therefore somewhat related to how much I like the bit of land alongside, because I'll be pulling in there very often. Probably if I had a big cat or any bigger boat, my enjoyment wouldn't be so shore-related, but however long the time spent sailing from place to place, I reckon I'll enjoy retaining the option to dry out when I get there.

 

[snowleopard]

You dont dry out any boat deliberately without knowing whats underneath, not if you are wise.

The first time I went into Boulogne I tied up where the fishing boat is in this photo while I went to the capitainerie to ask for a berth. Someone came rushing over to tell me not to berth there. When the tide went out I realised why - it dried to a pile of huge boulders.

 

[snowleopard]

On the wholly secondary question of whether boats which dry out, ought to be able to flush their loos and contain their waste when dried-out, I'd agree it has to be each owner's choice, depending on how often he anticipates needing that ability, and whether he wants to lay out the cost of the system/additional tankage it will require...

...and I can see that the cost of acquiring that ability may well be about the same aboard a 24ft yacht, as on a 48fter...yet it'd possibly be a prohibitive proportion of the smaller yacht's total value. A pity, since the smaller yacht is far more likely to have need of it, being better suited to drying out.

I've admitted how unfamiliar I am with yacht lavatories, and their plumbing. I can only say (however odd or unusual it may make me sound) that when I have a yacht which can dry out, I shall do so as often as possible, in scenic and remote places which I'd certainly never want to pollute. So, rare as my choice may be, I'll be supplementing the tankage in order that the loo continues to flush into a capacious holding tank, even in those lovely surroundings.

Remember cats don't need ballast. Our keels are hollow with a capacity of around 200 litres each. They are our holding tanks. With 440 litres of fresh water it is straightforward to use the shower hose to provide flushing water so we can be dried out for several days without needing to pump.

 

[Greenheart]

Remember cats don't need ballast. Our keels are hollow with a capacity of around 200 litres each. They are our holding tanks. With 440 litres of fresh water it is straightforward to use the shower hose to provide flushing water so we can be dried out for several days without needing to pump.

Interesting and instructive...when such an option is possible without much deep thought or serious investment, I'm still surprised it isn't a commonplace use of the space. :encouragement: