Perfect sized catamaran for ocean sailing is 40ft!

[contrail]

Originally Posted by Kamen

Are you sure? I don't think the righting moment goes up exponentially. Pretty sure it is a polynomial (of 4th degree) function of the linear dimension. Mass goes up with the cube of the linear dimension and the leverage is linear with respect to size.

I am sure you are right....and I am not a mathematician. What I meant is that stability is increased more quickly than size, if you get what I mean!

[smj]

Originally Posted by arsenelupiga

that is definitely consideration comfort and structure stress.



however there is more than 1 way to skin the cat.



on one side you have thin hulls high bridgedeck. Works great until seas are really up. this type of boats display side instability in such conditions. Thin hulls and high bridgedeck allow large side swings.



wide hulls smaller bridgedeck and nacelle, receipe of condomarans works as well without instability. Reason is as hulls are wider, bridgedeck is narrower and needs less height to achieve same level of efficiency as thin hulls high bridgedeck.

As hulls get wider the bow wave gets bigger. The narrower the bridgedeck spacing makes the bow waves converge under the bridgedeck which lessens the bridgedeck height while underway.

[arsenelupiga]

Originally Posted by smj

As hulls get wider the bow wave gets bigger. The narrower the bridgedeck spacing makes the bow waves converge under the bridgedeck which lessens the bridgedeck height while underway.

makes sense. But that convergence is just under nacelle and doesnt produce any slamming as nacelle cuts it in half under angle. Hulls on the other side lose wetted surface - walley of water created - and therefore probably bit faster. But have not observed any other boat so cant compare.

[fxykty]

Originally Posted by toolbar

Do you actually raise your 90+ sqm mainsail without an electric winch?

On my comparably sized main made with Dimension Polyant DYS that is a major pain - it is be possible to raise it with a winch, but I wouldn't do that for fun.


Paul

We have an 80sqm mainsail in HydraNet and with six round fibreglass battens. All up I guess it weighs about 100kg, given it was about 85kg rolled up to take to a sailmaker for servicing. With head to wind for initial hoist I can jump it to the cunningham hole, then winch it the final 40cm and tension, with a 2:1 halyard. Total hoist is 17.9m. My wife does not choose to do this hoist by hand and does use the winch the entire way when she does. She has used the windlass rope drum and thinks that’s the bee’s knees - with our electrical upgrade she’ll be able to run the windlass without the engines running so I expect she’ll use the windlass more for that purpose.

For reefing and unreefing we use the winch and that is an easy singlehanded evolution.

We are getting a new mainsail and jib, both membrane string sails with relatively heavy taffetas on both sides. With six carbon box battens we figure the overall weight will be half of the mainsail it’s replacing.

[fxykty]

Originally Posted by Tupaia

So you have an ELECTRIC windlass - I rest my case.

Raising a fully battened mainsail bigger than 60sqm (about the norm for a 40ft cat, Lagoon 40 has 56sqm) is PITA for the smallest member of the crew. Monos tend not to have fully battened mainsails.

I suspect your boat has close to 80sqm main and I bet it is a real joy to raise manually. How often does your better half raise your mainsail on her own? I bet it is nearly always a task that you take on.

Anyway my point was to give a reference to the "rather outdated" reasoning behind the 40ft statement. It is not a rule just a very rough guide by defining the point at which a catamaran becomes more technical.

No one is saying that larger boats such as yours cannot be handled without mechanical aids they just become more demanding for the average sailor at around 40ft.

I certainly wouldn't say that a 40ft cat is the ideal size for ocean cruising.

Is an electric windlass not standard equipment in the average 40 foot cat?

Our cat is relatively simple and has less equipment and space than the average 40 foot cat - we had chartered a Leopard 40 just before we bought our boat and that was a much larger boat inside and certainly more complicated with AC, 2 generators (to run said AC), 4 electric heads, electric dive compressor, etc.

Our boat is perfect for two, OK for four, and short term only with more than six. Works for us.

[arsenelupiga]

Originally Posted by fxykty

We have an 80sqm mainsail in HydraNet and with six round fibreglass battens. All up I guess it weighs about 100kg, given it was about 85kg rolled up to take to a sailmaker for servicing. With head to wind for initial hoist I can jump it to the cunningham hole, then winch it the final 40cm and tension, with a 2:1 halyard. Total hoist is 17.9m. My wife does not choose to do this hoist by hand and does use the winch the entire way when she does. She has used the windlass rope drum and thinks that’s the bee’s knees - with our electrical upgrade she’ll be able to run the windlass without the engines running so I expect she’ll use the windlass more for that purpose.

For reefing and unreefing we use the winch and that is an easy singlehanded evolution.

We are getting a new mainsail and jib, both membrane string sails with relatively heavy taffetas on both sides. With six carbon box battens we figure the overall weight will be half of the mainsail it’s replacing.

+ 2 gennakers if i remember correctly + rig upgrade

wow, that is a serious upgrade you doing there!

Wonder what will the net effect be on sailing abilities of your boat.

[fxykty]

Originally Posted by arsenelupiga

here you go



link



https://puc.overheid.nl/nsi/doc/PUC_2381_14/3/



Rule 27 Vessels not under command or restricted in their ability to manoeuvre



(g) Vessels of less than 12 metres in length, except those engaged in diving operations, shall not be required to exhibit the lights and shapes prescribed in this Rule.





But then in

Rule 30 Anchored vessels and vessels aground

(a) A vessel at anchor shall exhibit where it can best be seen:

(i) in the fore part, an all-round white light or one ball;







wtf, how can one follow if rules are not even clear

There are the International Rules for Preventing Collisions at Sea, which must have national legislation in each country where they are to take effect. Each country can modify them as it sees fit, but most don’t. I would suggest you follow the Australian rules: https://www.legislation.gov.au/Details/F2016L01187, which basically says that Australia follows the 1972 International Rules. Each state can make changes, generally minor like NSW declaring commuter craft zones.

Finding an actual copy online is not easy, so I’ve linked and pasted the NZ legislation. It doesn’t change the International rules at all for the day shapes section.

https://www.maritimenz.govt.nz/rules...itime-rule.pdf

22.30 Anchored vessels and vessels aground
A vessel at anchor must exhibit where it can best be seen—
(a) in the fore part, an all-round white light or one black ball; and
(b) another all-round white light at or near the stern at a lower level than the light in the fore part;
BUT if the vessel is less than 50 metres in length it may exhibit an all-round white light where it can best be seen instead of the lights referred to in subparagraphs (a) and (b) of this paragraph.
A vessel of 100 metres or more in length must also use the available working or equivalent lights to illuminate its decks when at anchor. Any other vessel at anchor may do so also.
MNZ Consolidation 31 March 2021
16

(3) A vessel of less than 7 metres in length at anchor, not in or near a narrow channel, fairway, anchorage, or where other vessels normally navigate, is not required to exhibit the shape prescribed for a vessel at anchor.
(4) A vessel aground must exhibit the white light or lights for a vessel at anchor prescribed in rule 22.30 (1), and in addition, where they can best be seen—
(a) two all-round red lights in a vertical line; and
(b) three black balls in a vertical line.
(5) A vessel of less than 12 metres in length, when aground, is not required to exhibit the lights or shapes prescribed in 22.30(4) for a vessel aground.

The take away - every vessel no matter the size must show a black ball when at anchor (except <7m if somewhere where other larger boats don’t go). No exception for <12m.

[s/v Jedi]

Did I read that guys let their wife do the work on deck, hoisting sails, anchoring etc. ? Just so you get to hold the wheel? May be not so strange when the wife tells you she doesn’t fancy sailing so much...

Also, what is wrong with using a winch? Why do you think you need to hoist a sail without a winch? I have a pretty big boat and I have electric winches, but when I stick a handle in I can pull more weight than on electric. Also, you can just buy an electric winch handle and make any winch electric.

Then we get to the windlass: oh they have an electric windlass, how bad is that! Really?! The only difference between an electric and manual windlass is the speed at which you can haul. Same for a winch.

Any decent boat has a fully battened mainsail.

[s/v Jedi]

Originally Posted by fxykty

There are the International Rules for Preventing Collisions at Sea, which must have national legislation in each country where they are to take effect. Each country can modify them as it sees fit, but most don’t. I would suggest you follow the Australian rules: https://www.legislation.gov.au/Details/F2016L01187, which basically says that Australia follows the 1972 International Rules. Each state can make changes, generally minor like NSW declaring commuter craft zones.

Finding an actual copy online is not easy, so I’ve linked and pasted the NZ legislation. It doesn’t change the International rules at all for the day shapes section.

https://www.maritimenz.govt.nz/rules...itime-rule.pdf

22.30 Anchored vessels and vessels aground
A vessel at anchor must exhibit where it can best be seen—
(a) in the fore part, an all-round white light or one black ball; and
(b) another all-round white light at or near the stern at a lower level than the light in the fore part;
BUT if the vessel is less than 50 metres in length it may exhibit an all-round white light where it can best be seen instead of the lights referred to in subparagraphs (a) and (b) of this paragraph.
A vessel of 100 metres or more in length must also use the available working or equivalent lights to illuminate its decks when at anchor. Any other vessel at anchor may do so also.
MNZ Consolidation 31 March 2021
16

(3) A vessel of less than 7 metres in length at anchor, not in or near a narrow channel, fairway, anchorage, or where other vessels normally navigate, is not required to exhibit the shape prescribed for a vessel at anchor.
(4) A vessel aground must exhibit the white light or lights for a vessel at anchor prescribed in rule 22.30 (1), and in addition, where they can best be seen—
(a) two all-round red lights in a vertical line; and
(b) three black balls in a vertical line.
(5) A vessel of less than 12 metres in length, when aground, is not required to exhibit the lights or shapes prescribed in 22.30(4) for a vessel aground.

The take away - every vessel no matter the size must show a black ball when at anchor (except <7m if somewhere where other larger boats don’t go). No exception for <12m.

Correct. That talk about not needing the ball in an anchorage is the same as for the anchor light... it’s about what they call a “designated anchorage” and I’ve only ever found those in the US. Anywhere else a place where boats anchor is called an anchorage and ball day signs and light night signs are mandatory.

[arsenelupiga]

Originally Posted by s/v Jedi

Correct. That talk about not needing the ball in an anchorage is the same as for the anchor light... it’s about what they call a “designated anchorage” and I’ve only ever found those in the US. Anywhere else a place where boats anchor is called an anchorage and ball day signs and light night signs are mandatory.

thanks for clearing this up. just could not find definitive answer. i just bought one.

while i have your attention...
Vessel under sail and power - one needs to carry cone if boat is >12m. Is this true ?

[Tupaia]

Originally Posted by s/v Jedi

Did I read that guys let their wife do the work on deck, hoisting sails, anchoring etc. ? Just so you get to hold the wheel? May be not so strange when the wife tells you she doesn’t fancy sailing so much...

Also, what is wrong with using a winch? Why do you think you need to hoist a sail without a winch? I have a pretty big boat and I have electric winches, but when I stick a handle in I can pull more weight than on electric. Also, you can just buy an electric winch handle and make any winch electric.

Then we get to the windlass: oh they have an electric windlass, how bad is that! Really?! The only difference between an electric and manual windlass is the speed at which you can haul. Same for a winch.

Any decent boat has a fully battened mainsail.

Totally agree. Which is why I said that 40ft was a rather outdated measurement that originated in the early 1990's when cats started to gain traction in the mainstream but when electric winches and windlasses were not the norm and it is at this point that mechanical aids become increasing necessary.



IMO the optimal size catamaran for ocean sailing based on a couple is between 40 and 50ft. There are obviously outliers both longer and shorter but they are not the norm.

[chrisr]

Originally Posted by s/v Jedi

Did I read that guys let their wife do the work on deck, hoisting sails, anchoring etc. ? Just so you get to hold the wheel? May be not so strange when the wife tells you she doesn’t fancy sailing so much...

not much to disagree with here however our owner (aka my wife) does most of our work getting the main out and never complains

of course it's in-mast furling so it's just a matter of pushing the button...

but seriously : technology has made it much easier for couples to handle bigger boats at sea. the problems i believe are in port...trying to fit a big cat into most places is not fun...neither is lugging heavy gear ashore...or getting under bridges...the list goes on

cheers,

cheers,

[Piscis]

Originally Posted by arsenelupiga

thanks for clearing this up. just could not find definitive answer. i just bought one.

while i have your attention...
Vessel under sail and power - one needs to carry cone if boat is >12m. Is this true ?

My post above was only targeted to this.

As far as i read the Col regs, the 12M rule does not apply to that rule. So a Sailing vessel under sail and motor or under motor only must show the cone in any case, regardless of length...

[valhalla360]

Originally Posted by contrail

I am sure you are right....and I am not a mathematician. What I meant is that stability is increased more quickly than size, if you get what I mean!

If all else is equal, then a bigger, heavier wider boat is more stable. Problem is all else is never equal. Bigger boats come with bigger rigs that can generate greater overturning forces, so it's not so simple.

Of course other design considerations often result in a more stable boat but it's not intrinsic to being larger.

40ft give or take a few feet is a good starting point for newbies who don't know what they need.
- You can go smaller but it's cramped living and slower speeds. As 30-34ft boat can be quite comfortable coastal cruising where you can get off the boat most days but 2-4 weeks at sea it gets tight.
- You can go bigger but it gets expensive with little gain in comfort for a couple and you become more dependent on mechanical devices which can and do fail. It also becomes limiting for coastal cruising where you can't get into places a smaller boat can get into and it's the rare cruiser who spends most of their time on ocean crossings.

[44'cruisingcat]

Funny that people are taking this article seriously!

You really can't generalize. For a start, there is no standard sailing couple. Some are young, some older, some fit, some not... Some couples are really one person single handing most of the time...

IMO, a better indicator than length of how easily a boat can be sailed would be it's working sail area. Some relatively short boats are heavy and need big sails, some longer boats are light and only need comparitively small sails.