hull material choice for blue water

[Ben Dockrell 22]

As others have mentioned, all materials have advantages and disadvantages, you need to pick the one that suits your needs best.

Personally, I'd suggest that a well-maintained steel boat is probably the most easily available and cost-effective option. If you can find a good ferrocement one (and they do exist), then that's another good option. Although both methods of construction can produce heavy boats, if you're looking at anything 40 feet or longer, the difference between heavily built GRP and either steel or ferrocement gets increasingly small and irrelevant. You've already discounted wood, so I won't try to change your mind, although if somebody wants to do blue water in a wooden boat, there are plenty out there that will do the job fine (there's one called Suihaili for starters, although I don't think she's for sale).

If you're worried about hitting submerged objects at sea, then rather than worry about what to build the hull from, why not just get a boat that you like and is generally suitable, and install a forward-looking sonar? The last time I looked £1,500 would buy a top of the line (at least for civilian use) one, and they are available a fair bit cheaper than that.

I bet no-one in any government today* has been approached by anyone who wants to begin a project which surrounds all dangerous reefs and other hidden dangers with a heavily bouyed (layers of padded bouys) baracades which are designed to bring boats of size to a stop from which they reverse themselves out of and alert the relevent authorities.

The barrier works very much along the lines of racing cars going into mounds of used tyres until they come to a stop.

There would be different classes of them as judged appropiate for the danger present.

*I mean in terms of anyone in any government taking any notice.

 

[Blueboatman]

My two hporth.
In some ways strength decreases with size. A well built 20 footer will bounce off things, having a lot less inertia.
I have been through the edges of a couple of scary hurricanes in a wee boat- so no more than 70kn sustained. It is heartbreaking to see well prepared large boats destroyed by hastily parked well insured average yachts n mobos with massive windage and poor ground tackle dumped at last minute into overcrowded anchorages. For this reason steel has clear merits- and can be taken to sea if preferred, or like me the trick was to draw so little water that you can 'park' in shallow uncrossed creeks where dragging yachts ain't going to be such an issue. ( lowering the mast helps too obv).
To the OP . Catamarans have been known to become airborne and capsize in serious tropical storms too, regardless of what they are made of!

 

[mitiempo]

...or like me the trick was to draw so little water that you can 'park' in shallow uncrossed creeks where dragging yachts ain't going to be such an issue.

Like the Ovni or the other French designs with centerboards/lifting keels. This is a Boreal

 

[alahol2]

Like the Ovni or the other French designs with centerboards/lifting keels. This is a Boreal

So what's preventing that from crushing the kiddy to pulp???

 

[mitiempo]

Why would it - it's stable on a wide keel box. They don't fall over.
http://www.voiliers-boreal.com/

 

[Ben Dockrell 22]

I think that photo was "photo shopped" they deleted the supports by the looks of it.

 

[mitiempo]

Supports aren't necessary. The keel box houses all heavy loads - ballast, engine, batteries, and tanks. It is wide enough with the skeg's support to keep the boat stable when beached. It was part of the original design of the boat.

 

[Ben Dockrell 22]

Supports aren't necessary. The keel box houses all heavy loads - ballast, engine, batteries, and tanks. It is wide enough with the skeg's support to keep the boat stable when beached. It was part of the original design of the boat.

Very interesting boats

 

[Blueboatman]

Such an intelligent concept. Quick too

 

[Bajansailor]

Still think concrete myself, good thick concrete hulled large boat. The outer area would have concrete bars along the hull area. Bit like a car with bull bars but much bigger. not built for speed just for safety unless someone collides with you in a grp of course, if your not awake at the time you,d probably not hear or feel the bump

Re concrete hulls, I shall leave you to form your own opinion of El Lobo's hull in the link below :
http://el-lobo.co.uk/html/april_2009.html
Here they describe how they had an encounter with an errant jet-ski at speed while quietly anchored in Tobago - the photos in the link (further down) illustrate the damage sustained.

 

[Ben Dockrell 22]

Re concrete hulls, I shall leave you to form your own opinion of El Lobo's hull in the link below :
http://el-lobo.co.uk/html/april_2009.html
Here they describe how they had an encounter with an errant jet-ski at speed while quietly anchored in Tobago - the photos in the link (further down) illustrate the damage sustained.

Unfortunately although i can see the smaller photos they wont enlarge when i click on them.

I know im only stating the obvious here but some folks will critisize concrete hulls saying if you have an accident your going to get a chunk taken out of the hull,while that can be the case why dont they just take a look at the other guys grp boat or thier jet ski