Heavy vs Light Displacement

[andreavanduyn]

Now as Carbon fibre has proven its long lasting quality and strenght why is it that us cruisers still buy heavy displacement yachts?

Based on the upwind 'performance' needed when being on the low side of the pond with wind blowing you towards land?

[sailorboy1]

We buy what is available and what we can afford. How many affordable carbon fiber cruising boats are there?

But as far as displacement goes there is more to the issue than the 'weight" of the boat as far as just the sailing performance. There is always going to be a comfort factor gained by the displacement and a lot of times the displacement can be off-set by sail area. I've notice that on lots of boats I been looking at, which I orginally disregarded because of high displacement, that the displacement/sail area is just as good and the boat probably sails just fine. But I still disregard real light boats because I don't really want to sail on the edge all the time.

[andreavanduyn]

agree that they are not available yet but if not carbon then 'infused' epoxy yachts save lots of weight as well.

Price is not the issue this is a theoretical question of my side...ie how conservative is our world of yachties and or based on what criteria one buys his 'dreamyacht' these days.

[sailorboy1]

I think if the price was right to make a market then cruisers would accept it as far as a material goes without much problem. If we didn't we all would still be sailing full keel wood tanks instead of fibergalss. I guess after price the next factor as far as carbon fiber would become the ability to repair in some far off place. The weight of the hull material really doesn't matter all that much as it still comes down to a displacement value as to cruising boats for lots of factors. So for me if carbon fiber was a proven material for cruising and I could repair it if needed, then if the price was right compared to some other material I would consider it a plus.

[S&S]

Ease of motion, stability in a seaway, etc.

By itself, light displacement is not the be-all/end-all for cruising boats.

[Joli]

Weight gives you a softer ride and punch to bust through when going upwind. A planning boat is great but do you really think the cruising sailor is gonna push a boat to do that?

Here's the scenario: the breeze is 145 twa and its blowing 25 to 35 knots. The light weight planning boat easily hits speeds in the mid teens so the apparrant drops to 10 to 20. To get speed you need to add power, which means you have to fly an assy or code 1. Since your cruising you have the autopilot set. Guess what? The auto goes tits up and you crash jibe the boat at 3 in the morning, and I gaurantee that is when it happens. The boat is now on the wrong board, spreaders in the water, broken boom, and you are faced with trying to get the assy back aboard while pinned to leeward.

How do you avoid this? Easy, go 6-7 knots with a minimum amount of sail that lets you recover when (not if) the auto crashes. So you may as well buy the heavier boat and slow down.

[Factor]

I'm with Joli (Oh my goodness - was that me saying that) for all the reasons he mentioned


speed is good but for cruising when I get to 8-10 knots I start to slow her down, its too hard to keep pushing in double figures for a couple cruising (well its too hard for us). Having said that - being able to actually sail in 10 knots of breeze is a must. MY aim is 7.5 knots as often and consistently as I can.

[sneuman]

A week ago Saturday, a buddy of mine and me and few others set out for the Good Old Boat race in my friend's Mariner 31 ketch.

The day, albeit unusual for the Chesapeake, was blowing 25kts, perhaps gusting a bit more.

Granted, most of these people were not racers, but the carnage in the fin keel classes -- boats out-of-control -- was impressive, to say the least. It eventually caused the RC to scrub the race. Meanwhile, we had a very nice jaunt back to the marina in 4-5' chop. No drama and never a worry.

Now, most of the time the fin keelers would have had a better and much faster time of it, but in those conditions, the weight really makes a difference.

[andreavanduyn]

Joli and fans of the heavy displacement following from experience to spice this discussion (thank you for participating )

I have sailed more than one carbon sailing yacht with heavy keel (40+%) and enjoyed the planing but funny enough realized that they were easier to sail than my own heavy displacement S&S
The forces go into speed and my wife handled the yacht even in the harbour these modern yachts turn around their keel so docking is easier than ever...

Coming to your valid point that the carbon /light weight racers suffer in racing this is correct as they are built to the limit and raced by racers....another breed and mostly better dressed than skilled (i used to race as crew and ended up owning /steering racers so speak of experience)

MY POINT IS that if these light displacement yachts were produced for cruising with a heavier keel with more surface and not IMS designed but with volume in the nose and lesser flatter bottoms WE might enjoy them

[gonesail]

the light boats get tossed around more and therefore are rough on the occupants of the boat. as Joli said: a soft ride and ability to punch thru. then there's the money thing.

[andreavanduyn]

But when well constructed ? How come J-boats and especially the big ones stay with the owners long term and cruise next to racing?

heavy well proportioned keels make a light boat behaving alike a heavy one in rough weather without the forces on mast /rigging

[S&S]

In a short chop, that flat ULDB bottom is a filling-loosetener for sure. Keel weight is not the only thing. A high proportion of displacement in the keel (usually) means quick motion. Also, thin fins with a bulb are notorious for dropping keels.

[Cheechako]

One reason might be that Carbon Fiber has had some very publisized problems. There was the Americas Cup boat that broke in half in light air, there are always Americas Cup boats on TV showing CF booms breaking in half. These are very highly engineered craft. If someone wants to sell CF boats they are going to need to convince the buyers that they are using CF to make the boat stronger, not lighter....

[Jesse]

The circumnavigation by young Micheal Perham might provide a decent look into this question. Could it be considered a cruise or a race? At one point he was moving at 24 knots and considered it comfortable and reported no trouble at all sleeping while surfing down the face of rather large waves. Definitely not for me but he seemed to thrive on it.

[Paul L]

Originally Posted by Joli

......How do you avoid this? Easy, go 6-7 knots with a minimum amount of sail that lets you recover when (not if) the auto crashes. So you may as well buy the heavier boat and slow down.

Maybe so, but the the 'minimum amount of sail' on the medium weight modern design offshore boat is going to be a lot less sail than what is required for the heavy weight classic cruiser. Less sail is much more manageable by a small Mom and Pop crew. In addition, that classic is probably going to be wallowing or motoring in the light air while the modern boat is sailing along at 3 or 4 kts.

Paul L