The old hull types conundrum

[MapisM]

It has been done to death, I know.
But during the last months, I paid even more attention than usual to the behavior of any boat I've had the opportunity to cruise on - also in view of possibly changing the old tub.
Btw, all my impressions were perfectly aligned with SWMBO, who is not technically minded at all but is much better than myself at perceiving even the slightest comfort differences.
And we reached the very same conclusions:
1) stabilization is great, and we don't want to live without it. But that's not breaking news, of course.
2) in several conditions, the hull shape is as critical for comfort as is stabilization, if not more.
In other words, imho no P boat, even if stabilized, can come close to the comfort of D/SD hulls, for roughly comparable boat sizes.

The following short video was originally meant to shoot some dolphins that came to play with our boat, but by the time I found my mobile they were gone, and didn't reappear.
Otoh, I think it's rather good for explaining what I mean.
Forget the fact that the boat has zero rolling. That comes courtesy of the fin stabilizers, which are amazingly effective regardless of the hull shape.
It's the smoothness of the pitching that I strongly believe is impossible to get with any P boat, even if bigger (within reason, of course).
In fact, aside from being obvious that those guests sitting at the bow are not bouncing around at all, and they are not holding onto anything, there's another thing to consider:
I took the video while standing on the flybridge, and without any support to lean against - just standing, on my own.

Now, I'm aware that asking you to estimate how the ride would have been with your boats in those conditions, just looking at a video, takes a lot of guesswork and couldn't be more far from a scientific analysis. Also for myself, even if I was there, I can only guess how a P boat would have behaved, based on experience/memory.
That said, I have a very strong feeling that neither sitting comfortably at the bow, nor shooting a reasonably stable video, would have been feasible in those conditions, with a P boat.
So, over to you guys, wadduthink?

Oh, and before anyone mention, I'm aware that with a decent P boat it would have been possible also in those conditions to cruise much faster, hence reducing the pitching.
But I hope nobody will pretend that the ride would have been more comfortable overall, because I'm pretty sure that at 20+ knots you should have hold onto something for good, at least while standing or walking around - not to mention while shooting a video! :ambivalence:

 

[PowerYachtBlog]

All true what you say but you are judging the D/SD hulls in the prime environment i.e head seas.

It is basically as taking out any planning medium or deep Vee boat in following seas they will always perform more or less good.

As for stabilization, notably active fin stabilization, speaking with an engineer about them in recent weeks in there use on planning boats.
His opinion was that this is the new way to reduce R&D on optimal hull shape from some.
With some builders even asking the question that if you are using the boat in rough weather you should have them.


ps. That's a nice video.

 

[AndieMac]

I was certainly impressed by the Ant in the same waters, similar conditions a couple of years ago, a magnificent ride all round, head, beam and following seas, a very comfortable boat for long sea passages.
I know you are concerned with ongoing maintenance issues, but there is a lot to be said about the old tub, she has a very "proper" boat feel.

 

[Portofino]

Some big planning boats from Ferretti can have gyros fitted -so,s not to compromise top end speed .
I saw a Riva Ergo 68 last year in the yard having curved fins fitted -newish boat .
As PYB says -you can just plan round weather .
My Wife's a nervous boater --hence the deep V deadrise thing -it's certainly worked for her .
We recently sea trialled a Riva 52 off Monaco ---within 5 mins of leaving the harbour --upwind it's slammed about arround high 20's ----- Nope was the reply from wife !
I think it's all a compromise -if you want more of floating appartment like a 20-24 M older Italian lady -San Lorenzo , Akhir ,Canodos , Cant D Pisa etc -then they are planners designed to cruise in low 20,s guzzling 4-600 L/h
If you go @ D speed in one then maybe less than or arround 100-150 L/h ? ----but as you say ride may suffer ?

 

[scubaman]

That does indeed look a very comfortable ride considering the sea state.

Having experienced similar seas only last weekend my totally unscientific estimation would be that my boat, normalizing the difference in length, would have been more lively (and wet). With less mass it's more like a cork on the waves. And as has been discussed before, the second thing to note at displacement speed is the occasional slamming from the chines which can be surprisingly pronounced at times.

Turning beam on to the waves threw the cockpit table over but it's difficult to estimate how the behavior would have differed from an unstabilized displacement boat.

 

[Spi D]

I believe 'mass' and bow shape also above waterline are factors to consider. Displacement certainly does mean lot.

Ever tried a catamaran? I did, south of Great Barrier Reef, and found it surprisingly smooth.

 

[Deleted User YDKXO]

In other words, imho no P boat, even if stabilized, can come close to the comfort of D/SD hulls, for roughly comparable boat sizes.

I don't think anyone would argue that a D/SD hull is going to be more comfortable than a P hull of the same length in a head sea. P boats tend to have fuller sections forward for a very good reason and that is to stop the bow stuffing itself into a wave at 30kts. If you were able to make Ant go at 30kts, I'm fairly sure it would submarine into the first big wave it hit because there isn't enough buoyancy at the bow to hit a wave at 30kts and ride over it. Then there is the issue of weight. Again if you're going to make a P boat go at 30kts you're going to have to pay more attention to weight saving so size for size they're going to be lighter and pitch more into a head sea than a D/SD boat. The fact is that if you want a boat that goes at 30kts you're going to have to compromise on comfort into a head sea at any speed

 

[MapisM]

there is a lot to be said about the old tub, she has a very "proper" boat feel.

Blimey C, it hurts to hear that from someone who knows as much as you do about boats.
I've yet to finalize the purchase of our next boat, and I'm already beginning to regret that... :ambivalence:

 

[MapisM]

In other words, imho no P boat, even if stabilized, can come close to the comfort of D/SD hulls, for roughly comparable boat sizes.

...
The fact is that if you want a boat that goes at 30kts you're going to have to compromise on comfort into a head sea at any speed

Ermmm... Hang on... To summarise, we are saying exactly the same thing, aren't we!?

 

[MapisM]

With some builders even asking the question that if you are using the boat in rough weather you should have them.

LOL, name and shame, W!

 

[AndieMac]

Blimey C, it hurts to hear that from someone who knows as much as you do about boats.
I've yet to finalize the purchase of our next boat, and I'm already beginning to regret that... :ambivalence:

Yes, young Andrew was all over the concept of importing your boat into Oz as soon as you mentioned the possibility of selling/replacing her in June, in fact we all did!
Maintenance over here is a lot more affordable than the Med, even CF.

Edit: just thinking, wouldn't she make an exotic entrant to the Feb. '17 Oz Wooden Boat Festival in Hobart

 

[MapisM]

just thinking, wouldn't she make an exotic entrant to the Feb. '17 Oz Wooden Boat Festival in Hobart

LOL, it's safe to bet that there wouldn't be many other IT timber boats around, that's for sure!

It's a shame that the shipping costs more than likely would be higher than the boat value...
Why doesn't A consider to bring her down on her own bottom instead?
The old tub is far from perfect, but she's still very solid, and with a range in excess of 1500Nm I believe it would be technically feasible.
Of course, it would take months, and there are some stretches of water along the route where I would rather cruise knowing that there is a Navy destroyer nearby... :ambivalence:
But at his age, that would be a trip most of us old farts can only dream of!