Light vs Heavy boats

[Heron]

I guess part of the answer is the intended use of the boat. If you are doing weekend or even a couple weeks out at a time, you certainly can get by with a less "robust" vessel.

I used to have a 33' boat that displaces 5 tons and now I have a boat that is one foot shorter and displaces 10 tons. I loved my old boat most of the time as it was a dream to sail and easy to tack. However, when we were out a few times in rough water, she was unstable and pounded hard which was cause for some concern.

My current boat actually does pretty well in all wind conditions except if it is blowing less than 6 knots. At that point, she will just sit. However, anything over 8 knots and I can keep up with many boats of comparable waterline length. If it blows hard and the waves are building, my vessel is barely feeling any results of the worsening conditions. Best of all, my wife feels so much safer in the heavy boat over the light one and is more confident in doing more cruising. To me that is the best of all worlds.

Lastly, if you are going to cruise / live on a vessel for an extended time, you will need more gear than a weekend warrior. Overtaxing a light vessel with a lot of weight can dramatically effect performance AND safety. Beth Leonard says to plan for 2000 pounds of gear per person for distance cruising. At first I thought that number was rediculous but as I look at my inventory, I don't think she is far off. If I load up my 20,000 boat with 4,000 pounds, that is 20% of the boats weight. If I do the same gear with my old 5 ton vessel, that is 40% added weight. I know my old boat would not be happy carrying 40% of her weight at sea.

HERON

[delmarrey]

Originally Posted by Heron

If I do the same gear with my old 5 ton vessel, that is 40% added weight. I know my old boat would not be happy carrying 40% of her weight at sea.

HERON

And one would most likely be compromising the rigging..................._/)

[btrayfors]

As has been noted, lighter boats accelerate faster. However, they also decelerate faster!

It's not true that a lighter boat will always win out in light airs. Depends on the boats, the conditions, and the sailors. Heavy boats keep on going after the air puffs have quit. They also keep going through headseas when lighter boats are stopped dead.

A well-designed, well-sailed heavy boat can be a tough contender in both light and heavy air conditions.

I assume we're not talking here of modern ocean racing boats like the Open 60s, which are real sleds (which can sustain speeds in excess of 30kts), but of the average crop of cruising boats one finds these days.

Bill

[Cruisingdad]

Hello Bill! How are you? Good to see you around.

- CD

[Pblais]

WHen the wife moves in with the pots and pans, well, you get the picture!

Actully better it is to not get the picture!

[btrayfors]

Hey, CD.

I've been around, most days. Hiding inside from the horrid weather.

But, today was great....62 degs F and sunshine. Took a mini-road trip to the Bay to see a friend's boat and my son's new boat.

Spring can't be far off :-)

Cheers,

Bill

[jim lee]

Light & Heavy..

One thing, a light boat can have less wetted surface area. This is a bigger factor in light wind. How much carpet do you want to drag through the water? This tends to help the light weight hull in lighter air.

Another is that hull speed is not a rock solid number. It seems that for some boats, this number is "spongy-er" than others. A light weight hull seems to have a better chance of pushing further into the hull speed barrier. (Before planing.) Favoring the light weight hull in heavy air.

But...

Light weight hulls are typically not designed to carry heavy loads. So, this may make them pretty touchy when it comes to carrying stuff with them.

-jim lee

[roverhi]

Light weight boats tend to have short/deep keels, flat sections, no bilge, spade rudder, exposed props, etc. All fine things for going fast in ideal conditions.

Unfortunately, going fast is not the cruisers primary concern. A cruiser is more concerned with getting there in reasonable shape, despite the weather. The flat bottomed boats have no bilge sump. Even very small amounts of water will get rolled up the sides of the boat so almost everything in the boat is at risk of being soaked. That's not a recipe for a happy passage, safe storing of food, tools, etc, and longevity of any salt susceptible gear like electronics.

Another problem with flat bottoms is they often tend to pound going to weather. I know, cruisers don't go to weather but when they have to, they often do it for days on end. When we had to go on the wind for 5 days to lay the Marquesas, I was very thankful that our fat boat didn't pound. Can't imagine the effect of 120 hours of a constant pile driving against the hull on my nerves, let alone the structural integrity of the boat.

I was even more thankful for the easy motion of our fatty after those 5 days. The slack bilges don't make for an initially stiff boat but they did make for an easy predictable motion that didn't toss us and our gear all over the boat. The deep keels, especially those with a bulb of some sort, wide beam and flat bottom make for a very abrupt motion. The righting forces multiply at very shallow angles of hear trying to force the boat upright. That is in contrast to a slack bilged boat where the forces ramp up slowly and are felt more gradually. This greatly reduces the abruptness of motion and lessens crew fatigue. Both types of boats will probably get there, one will have a worn out frazzled crew, the other will be ready to take on the mangos.

The issue of speed is an interesting one. In our W32, our worst days run was 11nm, mostly current, in the ITC when their just wasn't any wind. Our best was 177nm on a 6 day run into Hawaii from Tahiti when we covered 900 miles in six days. Our daily average for more than 10,000 miles was 118nm, through the water, with virtually no engine time. When we sold the boat after 10 years, engine hours were just above 500 with most of that for battery charging. Not a bad average for a fat, heavy, square brick. We made a number of passages at the same time as a variety of different boats, mono, multihull, ex and current racer, etc. We consistantly got their as quickly and often sooner despite giving away as much as 10' of water line length, number of crew, etc. We even smoked a 1 ton class WORLD CHAMPION on a reach. Would we win an around the buoys inshore race, no way, even with a tremendous handicap. Would we be wallowing at sea on a long ocean passage while a lightweight flew to the destination, probably not, either.

We made those fast passages with a boat that was significantly down on her lines, something like 7 inches. We carried everything we needed for repairs, additional fuel, water, kerosene, and all our personal stuff, two dinghys, life raft, a years worth of food and consumables,etc, etc. When we finally moved off the boat after 5 years, the first house we rented didn't have storage to hold all our gear off the boat.

Somehow, I don't think an 8,000 pound lightweight would have been able to carry all our stuff, probably more than 1/2 it's weight, and been anything but a wallowing tub. Wetted surface, the primary reason for lighter boats better performance in light air, goes up drastically as you sink them deeper and deeper into the water. Our boat seemed to sail better and better as we loaded more stuff aboard.

Structural strength is another issue with fin keel boats. Moore 30's have been raced all over the Pacific and are a perenial favorite in the single handed races to Hawaii. Recently a Moore 30 set the around the Big Island record (they were the first to try it) so can't comment on their speed. Saw the boat hauled after completing the journey and talked with the owner. He was trying to figure out how keep the keel from falling off. The keel had begun to separate from the boat and they were only able to finish the record attempt, not become a rescue, thanks to the heroic effort of two bilge pumps. From what I"ve heard most of the lightweights have had keel attachment problems when driven hard. I know the 2 Hobie 33's that sail out of here have keel attachment issues when subjected to the short steep seas of our channels.

Even if the sea doesn't pound your lightweight to death, a grounding quite possibly will. There are only two kinds of sailors, those that have run aground many times and those that will run aground many times. The moment forces on the hull/keel attachment on a short keel are concentrated over a very small section of the hull. The longer the keel, the lower the stesses on the hull when subjected to a grounding. The forces are extreme in a short keel in a grounding and have to be very thoroughly engineered, built with the strongest materials, careful craftmanship, and integrity of the builder. Anyone along the line makes a slight goof and thousands of pounds of lead head for the bottom. That's not to say that full keel boats are the only way to go, just that very short keels are absolutely stupid for a cruising boat. BTW, it's not the sudden stop that usually causes the problem but the up and down pounding caused by the surf. As an example, a W32 tried to enter a west coast harbor on the wrong side of the jetty during a storm. The boat pounded in the surf for a couple of days, was filled with sand, driven ashore and left high and dry. Other than the water damage to the mechanicals, etc, and sand getting into everything, the only physical damage to the boat was caused by trying to tow the boat off the beach with a bull dozer in the salvage operation. Contrast that with a moderate displacement boat with a not so short fin keel that tried the same trick and ended up breaking up as the keel got driven up through the hull.

I like full keel heavy boats for their structural strength no matter what I or the ocean throw at it. The rudders are solidly attached to the keel where they have a much better chance of hanging in there. The length of the keel makes for a much stronger overall boat without resorting to extremely expensive engineering and material measures. Last but not least, long keel boats typically don't pick up on every crab pot, lobstrer trap, stray fishing net and anything else lurking to grab hold of your boat.

Lighter is fine for dinghy racing, doesn't necessarily work all that well in the real world of ocean sailing.

Aloha
Peter O.

[David_Old_Jersey]

Peter O

Always nice to read stuff based on actual experiance.

I bet you have a secret hankering for a Beneteau

[Paul L]

roverhi,
You make a lot of good points. Just to balance the other side of the argument a bit, I'll respond to some of them. It is easy to take the extremes of heavy and light and compare them. In reality, that is not what most people are actually sailing when we talk about lght weight vs heavy weight cruisers. I currently own a J/37 and previously owned an Alberg 35. Most people think of the Alberg 35 as a classic plastic cruiser. They hear J and think of a lightweight racer. The J is 2 feet overall longer and weighs 500-1000lbs more design weight than the Alberg. Comfort going to weather of the two boats, the J will slice through the water and rock much less. Downwind it will acts like it is on rails, as opposed to the wandering of the Alberg. As far as work to sail, the J is far easier. A lot of this is due to better rigging, hardware and the need to carry less sail to get the same performance.

As far as groundings go, I see there are 3 types of groundings. The first is the I'm poking around the anchorage or running down the ICW calm water grounding. Second is the we are going through an entrance, the seas 1-2 ft and run aground. The third is we hit a reef in the night and the seas are 6 ft and the wind is blowing 30. In the first case, both types of boats will be fine. The light one may (may) be easier to get off. In the second case the full-keel boat will usualy fair much better - again depending on how much time it takes to get the boats off. In the third case, both boats are screwed.

As far as going to weather. You are undoubtably aware of the number of heavy crusing boats that can't effectively be sailed to weather by their crew. Because of design, loading and experiance. Pointing higher and going faster may make that uncomfortable 5-day trip into an uncomfortable 4-day trip.

You obviously spent a lot of time skillfully sailing your W-32. Your 177 mile day is impressive, but clearly the exception. An avg of 118 mile days for a boat that fits in a 40 ft slip is just that, average or less.

Paul L

[jim lee]

Yeah! What He said!

-jim lee

[Alchemist]

On my return to NZ from Fiji last year I went past a light 38 footer (MINES A HEAVY 25 T FERRO 45FOOTER) wind 20-kn+ fwd of beam for 7 days. he commented that they where sick of the pounding I hadn't noticed any at all .heavy=comfort=well rested happy crew=bigger margin of safety

[delmarrey]

I've always considered building a submarine with sails.

[CaptainK]

Yeah!!

Just weld together a few huge propane tanks. And you got your a home made submarine.

Some person did that over around Santa Cruz, CA back during WW2. It still exists today as a museum piece.

[Tom967]

As a graduate Naval Architect who designed these things..You are dealing in the land of trade offs..Your theoretical speed is contingent primarily on your waterline..in theory 1.34 the sq root of your water line...Now your beam becomes an important factor in rig design to account for ability to carry sail..factoring in your draft..coupled with the above factors will determine your displacement.. In short a designer can then calculate the rig design and sail area based upon these hydrostats...

As been said a heaver displacement boat will accelerate slower..Draft and beam add not only weight but wetted surface..(more frictional resistance)
which is just one factor in evaluating a fuller keel from a fin keel.

Stating the obvious a light displacement boat will sail better..livier in light or light moderate conditions..when the wind picks up heavier boat comes alive..more stability less heal..more comfortable..

The optimum speed factor considerations on racing boats are a canoe shaped mid section..a deep fin with 0 degrees sweepback angle with a nasa #10 keel cross section....suggesting low residual resistance..low frictional resistance..beam for increased sail area..depth of keel to increase stability..draft and displacement factors..considered primarily to fairbody draft..but sleek fin..will give benefit of stability without the weight penalty tradeoff for sail carrying purposes..

That's why ice cream comes in 28 flavors

Now go out an find a boat you like and have fun..