What factors affect ride comfort on the water?

[hlb]

For more than 40 years Olesinski designs have been directed towards setting the standards for the industry. From 25ft sports boats to 200ft ocean-going superyachts, our designs are renowned for their sea-keeping qualities, efficiency, deep-V hulls and signature style.

 

[wipe_out]

Very interesting comments for everyone..

I will certainly get better at managing the 25 footer in less than ideal water.. Just need to play with it when I don't have any nervous passengers who look like they are about to have a panic attack as soon as they hear the engine revs climb a little..

For the next boat I can see there is going to be lots of deliberation on the compromises of the different hulls and lengths available (also within whatever budget is available at the time).. SD hulls seem like a good compromise but I am just not sure they will give me the speed that I like from time to time so maybe a deep V planing hull is the better choice but would be a little less "comfortable" in rougher water..

What sort of cruising and top speeds can be expected from 35-40ft SD boats? (I realise that depends on engines etc. but just an average number is what I am interested in)

Seems planing hulls in that size generally cruise at around 25kn and top is about 30kn..

Any change is probably at least a year off so I have time..

 

[hlb]

Very interesting comments for everyone..

I will certainly get better at managing the 25 footer in less than ideal water.. Just need to play with it when I don't have any nervous passengers who look like they are about to have a panic attack as soon as they hear the engine revs climb a little..

For the next boat I can see there is going to be lots of deliberation on the compromises of the different hulls and lengths available (also within whatever budget is available at the time).. SD hulls seem like a good compromise but I am just not sure they will give me the speed that I like from time to time so maybe a deep V planing hull is the better choice but would be a little less "comfortable" in rougher water..

What sort of cruising and top speeds can be expected from 35-40ft SD boats? (I realise that depends on engines etc. but just an average number is what I am interested in)

Seems planing hulls in that size generally cruise at around 25kn and top is about 30kn..

Any change is probably at least a year off so I have time..

Doubt if you will find an SD boat of that size, if you do, it will eat fuel like no tomorrow.

For the age of boat your looking at, think planing and around 20 knots, it may do a bit more, but depends how big it is.

An SD boat is nearer 10 knots, unless it is a life boat where fuel is not a question.

There are plenty of planning boats that will handle big seas, but at some point you need self draining decks. Many planning boats offer this to a point, after that your looking at some thing more like a submarine, which I did not think you were looking for.

 

[cryan]

The key is the Area of the Waterplane. The Waterplane is the area of the hull section at the waterline. Basically the smaller the Area of the Waterplane the faster you can go. The problem is that the smaller the Area of the Waterplane the more issues you have with rolling and load carrying ability. Planing boats have very large AofWp at slow speed but as they lift out of the water that area is vastly reduced. unfortunately it is reduced towards the stern which means they are liable to slam and fall forward in the same way as a divers flipper does when walking on land. The only way to avoid this slapping with a reduced waterplane is to reduce the AoWp longitudinally. Warships do this by being long and thin which is fast but suffer terrible rolling. Most commercial ships in need of speed (such as Container Ships) have vastly reduced AoWp at the Bow and Stern with a much larger AoWp in the middle to hold more cargo. One of the most successful compromises ever was the 19th Century Scottish Fifie fishing boats which are very slim from the water line down but very wide above to aid capacity and stability. Fast Cats are known as SWATH (Small Waterplane Area Twin Hull). This is where the whole ship is sat on top of two large torpedoes for bouyancy with the two legs being ultra small AoWp.

The point I'm trying to make is that when you choose your next vessel, look for a vessel that has the hull characteristics suitable for the type of cruising your going to be doing most of the time. If you plan to spend most of your time cruising with the family then you might want to forgo the planning hull for something a bit wider and rounder. if you want the above but still with a decent turn of speed then get something longer and narrower but still deep to counter act the rolling. Personally if I wanted something that the family could enjoy on a long cruise in comfort but I still wanted the occasional thrill then I would perhaps go for a nice displacement cruiser and a jetski or small RiB for myself.

 

[[2068]]

Olesinski hulls are great for fast boats, and almost-copies of them are to be found almost everywhere.
But if you don't need to do 35kts+, there are other ways.
e.g. Brooms are not so good at high speeds, but they have a very deep forefoot and flat stern sections for lift: net result is a hull that will do 22kts through almost anything. But not 35kts.
There's no substitute for mass and a deep V at the front in rough water.

 

[PowerYachtBlog]

For more than 40 years Olesinski designs have been directed towards setting the standards for the industry. From 25ft sports boats to 200ft ocean-going superyachts, our designs are renowned for their sea-keeping qualities, efficiency, deep-V hulls and signature style.

I do not want to put down Olesinski but his deep Vee (medium Vee actually, most of his designs are -20 degrees deadrise aft) remains a bit of a steal in my book from the Napier design, the designer of Bertram from the seventies, up until the nineties.
Bertrams designed by Napier do ride better to any Olesinski design anytime.
I also saw some Olesinski design which run pretty average due to bad weight distrubition to much bow high but you can never say if this his fault or of the builder in question.

Anyways so many good hull designers out there from Micheal Peters US, to Bruno Acampora from Italy (these two are among the best in the last years), Fabio Buzzi, Lou Codega, Hunt studio, Mannerfelt etc etc Just to mention a few name.

To return to the topic at hand a good ride would be a boat which rides pretty low in the water, quite straight, and is a very dry in a head or beam sea. Magnum and some models like the 45, 53 or old 63 and the Jim Wynn (actually Walt Walters) designed hulls of the past used to be pretty close in this. Old Sonny Levi (and his friends like Franco Harraurer) designs are also good in this, as are some Hunt designs....
Now a combination of those three is not so easy to find.... I would tell you it is easier to find in older boats then on newer models....

 

[MapisM]

For more than 40 years Olesinski designs have been directed towards setting the standards for the industry.

Huh? Now that's a bold statement, if I've ever seen one.
I'd be very interested to hear what sort of planing hull feature Olesinski invented which became an industry standard, because I can't think of a single one.

Otoh, why do you think that deep-V hulls are also known as Hunt hulls?
And why do you think Sonny Levi is the only folk to which the British RSA ever awarded an RDI in boat design?
Remember, commercial success is one thing - which B.O. achieved remarkably - but that has nothing to see with breakthrough engineering. Not necessarily, anyway.

Edit: LOL, PoweryachtBlog, would you believe that I began my reply before you posted yours, then I had a looong phone call, and didn't actually see yours before posting mine?