50ft+ Hanse, Beneteau, etc slamming?

[NormanMartin]

LittleWing77, good stuff.

Leave on the I-65 trip in December. Much less rough than October or November by my experience.

[Nicholson58]

Good description L-Wing.

We had great luck on this transit in 2016-17 season on the fall rally with the Salty Dawgs. A late season storm tracking to Bermuda provided strong following wind and tall seas. We made over 500 miles in a two day run on mizzen and staysail only. 1500 miles total in 7-1/2 days on the rum line. Wave period was 18 and 16-20 feet. 9.5 up and 12 knots down, surfing a 40 ton dinosaur. Chris Parker advised us East for the last two days so we rode the trade wind in. Never tacked or jibed.

If anyone is contemplating the journey give the Salty Dawgs a look. It was a good trip, good planning, good assistance and a lot of new best friends.

https://www.saltydawgsailing.org/

[redneckrob]

Originally Posted by mglonnro

For me, "slamming" is when the (bottom of the) hull is momentarily out of the water and then "slams" into it.

I've been on some several hundred foot long several thousand ton vessels that experience "slamming" by that definition, so I'm not sure it can be avoided unless you're a submerged submarine!

[LittleWing77]

Originally Posted by mglonnro

Which accident are you referring to? This one?

Maritime New Zealand Report dated 21 July 2021 on the loss of the Vessel Essence on 14 October 2019

Wow, that's a sobering report (PDF attached below).

It's the second instance I've read where big windows combined with not fastening the window covers ahead of heavy weather were contributing factors.

Somehow, window-covers have just GOT to be made easier to install quickly! One of the surviving crew stated that the they did consider installing the window covers, but since the covers were attached by screws, they decided not to.

I can totally see that. Bad weather building and not wanting to have a crew member phaffing about on the sidedeck when there was a potential for knockdowns (which eventually did come - three of them)!

This was a Bavaria 47 Cutter. Not quite one of the boats Mglonnro is asking about. A Bavaria I would totally put into the ocean-going class. Hm.

Really sobering read.
LW77

[waterman46]

Look at the hull shape forward of the keel. A boat with more V shape forward does not slam in any sense compared to a short fin keel with just a gently rounded bottom forward. My current boat, if up to speed on a smoother interval, then we hit a big steep wave, up and over but no drop to a hard landing. Lots of spray and sometimes solid water over the bow, and the boat does slow a lot - you can feel the deceleration, but it is smooth, there is no sense of slamming at all.

I previously owned a boat that slammed a lot - its' a sickening sight when the hull is flexing relative to the deck, viewed from inside. The slamming could rattle your teeth. We sailed that boat several times up and down the San Francisco to Southern Cal route. There was some delamination of the forward bulkhead tabbing to the hull!

[wingssail]

Originally Posted by mglonnro

...For me, "slamming" is when the (bottom of the) hull is momentarily out of the water and then "slams" into it...

What I've been trying to say is that it's not the bottom that is slamming into the water, it is the side of the bow, and almost all boat have flat sided bows.

Further, the bow does not have to come "out of the water". Quite often the boat's forward sections simply slam into the next wave's face.

I don't see a lot of dramatic pitching (up in the air and back down onto a wave) except slower, heavier, boats with lots of inertia in the ends.

The slamming of modern boats is more like driving car car into a log lying across the road. You just hit it. "Bang!"

[goboatingnow]

Originally Posted by Searles

Read the report from New Zealand maratime report on the recent loss of a so called off shore modern cruiser racer ,conditions weren’t that bad or that good ,boat gave up big time ,result loss of owner skipper ,crew saved ,no need to read between the lines ,it’s all there ,

You mean the conditions that resulted in repeated knockdowns so “ conditions arnt that bad “ clearly you sail in a submarine

[goboatingnow]

In my experience slamming in modern boats is a function of forward speed slow down or put up with it.

[mglonnro]

Originally Posted by wingssail

What I've been trying to say is that it's not the bottom that is slamming into the water, it is the side of the bow, and almost all boat have flat sided bows.

Further, the bow does not have to come "out of the water". Quite often the boat's forward sections simply slam into the next wave's face.

Well, sitting inside the boat and listening to where the punches come, there are certainly also some coming to the bottom.. well in the boats I have been, none of them going between Sydney and Hobart

Here's a quote from the same paper I referenced earlier:

Joubert, in a paper published in 1982,
quoted several examples of failures of hull
bottom panels of different yachts, all of
which had been sailing upwind in steep seas
[11].

https://onepetro.org/JSR/article-abs...dFrom=fulltext

[goboatingnow]

Slamming is where the forward canoe body which in modern boats to enhance sailing performance ( less wetted surface ) is flat and hits the water , in the same fashion as the flat of your hand.

[Yellowtulip]

Originally Posted by Searles

Read the report from New Zealand maratime report on the recent loss of a so called off shore modern cruiser racer ,conditions weren’t that bad or that good ,boat gave up big time ,result loss of owner skipper ,crew saved ,no need to read between the lines ,it’s all there ,

In what sense did the boat “give up big time”? The report states that the owners had circumnavigated, presumably in that boat. It sank because the crew had not prepared a simple way of fitting storm covers on the port lights and were unable to do so in the prevailing conditions. While you could argue that the port lights were too big, perhaps, port lights can be breached on any boat if left uncovered.

[wingssail]

Originally Posted by Yellowtulip

In what sense did the boat “give up big time”? The report states that the owners had circumnavigated, presumably in that boat. It sank because the crew had not prepared a simple way of fitting storm covers on the port lights and were unable to do so in the prevailing conditions. While you could argue that the port lights were too big, perhaps, port lights can be breached on any boat if left uncovered.

Except mine, we don't have any.

[waterman46]

Originally Posted by wingssail

What I've been trying to say is that it's not the bottom that is slamming into the water, it is the side of the bow, and almost all boat have flat sided bows.

Further, the bow does not have to come "out of the water". Quite often the boat's forward sections simply slam into the next wave's face.

I don't see a lot of dramatic pitching (up in the air and back down onto a wave) except slower, heavier, boats with lots of inertia in the ends.

The slamming of modern boats is more like driving car car into a log lying across the road. You just hit it. "Bang!"

I hope you are right and that modern designs have improved. Our Cal29, a very "old" design, would get lots of air under the bow coming off a steep wave sailing upwind. If you were on the bow, you were weightless for maybe half a second - seemed like a long time! Then when she hit, yes she was a real slammer, right on the bottom.

[hpeer]

Well if getting slapped on the side is slamming then our tank gets the occasional slam. Once in a while a wave will catch us just right and we will get a, what I call a “Slap.” But that has to do with wave hitting a flat surface.

It is more prevalent in the 33’er, she has 3 chines so relatively bigger flat surfaces than the 44 which has 4 chines and some tumblehome.

I can attest that she being of the old heavy slow type will bury her bow and is much wetter than the 33.

[wingssail]

Originally Posted by waterman46

I hope you are right and that modern designs have improved. Our Cal29, a very "old" design, would get lots of air under the bow coming off a steep wave sailing upwind. If you were on the bow, you were weightless for maybe half a second - seemed like a long time! Then when she hit, yes she was a real slammer, right on the bottom.

It's not so much the design as the length of the boat relative to the size and period of the waves.

I was on my knees at the bow of an IOR 1/2 tonner (30 ft) doing I don't remember what. But I'd just changed into dry clothes and didn't have my foulies on (but I had my boots on) and the skipper wanted me to do some damnthing on the bow.

I saw a big wave and I knew the bow would be buried and I'd be soaked. I put my hands on the bow pulpit and stood up.

Next thing I knew I was doing a hand stand on the bow pulpit and looking over the front of the boat wondering if I'd get catapulted off.

The bow plunged down, about 8 inches under water, then came up to meet me as I nailed my landing on the now dry deck. Finished my job and returned to the cockpit cool as a cucumber, and dry.

I don't remember if it was slamming.