Sailboat hull types

[somethingrandom]

Hi



I'm starting to become a bit obsessed with the idea of ocean cruising(i dont own a boat and I don't know the first thing about sailing). Last night I was reading up about hull types and having a look at some boats for sale. I noticed that the vast majority of sailboats between 7-14 meters were semi displacement. The research I was doing seemed to suggest that for ocean cruising a full displacement hull would not broach as much as a semi. On the downside it would be slower going.



What hull type do most smaller ocean going cruisers come equipped with?

Is a full displacement hull a smoother ride?
Is a full displacement hull easier to handle?

Does a full displacement hull get knocked down more easily?
What's the smallest boat length that makes for a more comfortable ride?



Thanks

[Orion Jim]

Let the fireworks begin.....

[Pegu Club]

You might just want to consider learning to sail first, just sayin...

Fair winds,

[Don C L]

Welcome aboard somethingrandom!
Well for your first query right out of the gate you've really shot for the fences and opened up a can of worms! (to mangle a few metaphors!) There are quite a few discussions here about hulls and keels (which I think is central to your post.) Here is a good one:
https://www.cruisersforum.com/forums...sion-2930.html

and here are some more:
https://www.cruisersforum.com/forums...el-241824.html
https://www.cruisersforum.com/forums...el-243489.html

But really it is a little tough to give you a decent answer without asking how big a boat you are thinking of and where and what kind of sailing you are planning.
And really, once you start sailing, and trying out different kinds of boats yourself, you will be able to answer your own questions too. In everything there are trade-offs and compromises so there won't be one perfect boat. Many folks aren't willing to trade good performance for sea-worthiness, but to my mind that is a false dichotomy. There are many boats that perform well and would be generally considered very sea-worthy.
The heavier, or full, displacement hulls may not get knocked down as easily, but they are generally on the slow side.
Any boat can broach, but it sounds like your concern here is which boats are more likely to get knocked down or capsize. First of all it is good to point out that this is NOT a common occurrence, and given conditions where it MAY occur, most folks will opt to avoid that weather in the first place if they can, or use any number of tricks to wait out the weather, most of which do not involve getting knocked down.

[Pauls]

If you want to really understand the effects of differences in hull design I suggest you buy a copy of "Seaworthiness the Forgotten Factor" by Marchaj. There is no other reference that even compares. Marchaj was a national champion sailor, internationally recognized aerodynamicist, consultant to 12 meter teams, etc. It's a remarkable book, readable, understandable, and it addresses a number of things not touched elsewhere.

Also suggest you buy a copy of "The Nature of Boats" by Gerr. You'll learn a lot. The combination of these two works will give you a good understanding of the subject.

[Idlegreg]

I wonder if you are mixing up "Semi-displacement" with "Medium" or "Light" displacement.


In my explerience Semi-displacement is a term commonly used for power boats with hulls that can exceed the theoretical maximum of a displacement hull but which cannot fully plane (where the hull rises to be to some degree out of the water - not having to move its own weight in water aside as it travels and so able to go much faster). I think the term also implies that the boat has large engines providing lots of power to enable the potential higher speeds.

Assuming we are talking about larger sailing boats and not open dinghys. You can think of sailing boats as Heavy, Medium, Light and Ultra light. These terms are not tightly defined but if pushed I would say...

Some Light (and most?) Ultra light sailing boats can plane, primarily pure racing boats. Many others can surf above 'hull speed' and might be thought of as Semi-displacement.


Heavy and Medium displacement sailboats are pretty much confined to displacement sailing speeds (Some might argue with Medium there).


I don't think the likelyhood of broaching has got much to do with this difference of displacement - it is more to do with other aspects of the design and how the boat is sailed. I suppose light boats might be more likely to be pushed hard when racing, and that can lead to a broach.



An important thing to remember is that, unless you are good at spartan travelling, it is unlikley you will go long term cruising without loading the boat with a fair weight of supplies and gear. A Medium or Heavy displacement boat will not be much affected by that, while a boat that relies on light weight to perform well is going to be hobbled, so you may well lose the benefit you thought you were getting with a light boat.

[Don C L]

Sorry I see I didn't hit your questions. As far as smoother ride I think you are referring to "sea-kindliness" and this probably depends on whoever is judging it. But there are boats that have a reputation for sea-kindliness that are on the heavier side, with deeper keels. And as far as easier to handle my first thought was that you are referring to getting around in a harbor. Full keel boats don't back up well and they don't turn as fast as a fin keel boat, but, again, trade-offs.
Take a look at this website
https://atomvoyages.com/
for some ideas of smaller sea-going boats.
Personally I find the motion of a boat like mine, long keel, low interior volume and medium in terms of displacement comfortable, though I am often sailing at a 20 degree angle. Others would rather have a wider, beamier hull that is not heeled over as much. Also, a flatter, lighter displacement, hull will be fast but will slam more going upwind. That can be ameliorated by not pointing so high, but then you kind of lose the advantage you got with the fin keel and spade rudder that usually comes with that more modern hull. I always thought a hull like the Peterson 44 was a good all-around blend, but that is not a small boat.

[LittleWing77]

Originally Posted by Don C L

Also, a flatter, lighter displacement, hull will be fast but will slam more going upwind.

In which case, you'd better not be subject to seasickness at ALL - and know that about yourself...

[Idlegreg]

Originally Posted by LittleWing77

In which case, you'd better not be subject to seasickness at ALL - and know that about yourself...

I am not sure that Seasickness is related to slamming. I have an older heavy, narrow boat which never slams but I can get seasick at times.

I have also sailed on more modern boats, flatter and wider, which do slam upwind and while it is very annoying (normally would cause me to change course) I have not found it induces seasickness directly.

Of course the wide, flat floored boat, rolls less downwind and heels less upwind - I don't much mind downwind rolling so my boat is fine for me but some might hate it. I enjoy the heeling upwind when out for a day sail but multi day trips, when I might be heeled over for a longer period, living on board does get rather tiresome.

I believe it is very much horses for courses and those who have advised getting in personal seatime before worrying too much about what is the ideal boat in theory are absolutley correct. I think it is impossible to figure out which boat will suit you best from formulas and debates about the theory of yacht design. By all means take some account of that but I say, either go sailing as often as you can on multiple different types of boat, to establish what feels right. Or find a boat that excites you for whatever emotional reason and buy it - you will tolerate its bad points because you love it. Remember that no boat is free of vices (although some might get close maybe like the Peterson 44 mentioned above).

Some people like to go all the way and choose to cruise in a slow, heavy, but to them very comfortable boat, which can carry a huge amount of stores and gear without difficuty. Others go Ocean cruising in an Open 40 race boat or as one guy has sucessfully done in a tiny 21 foot Wharram Cat. These people have to travel very light but for those who do it I imagine it can be a blast.

As I said before if you are looking at smaller boats for longer trips then they are more likely to tend towards the heavier designs simply to have the carrying capacity, but it is not essential and many people have enjoyed cruising in small light boats.


Have fun :-)

[Pete7]

Originally Posted by somethingrandom

What hull type do most smaller ocean going cruisers come equipped with?

Fast ones, probably French because sailing to them isn't a hobby its a religion

[StuM]

Originally Posted by Idlegreg

I wonder if you are mixing up "Semi-displacement" with "Medium" or "Light" displacement.


In my explerience Semi-displacement is a term commonly used for power boats...

My thoughts too!