Southern ocean wave heights.

[Neptune's Gear]

The 30% rule is indeed the breaking crest height.
Wave height and length can break ships when they become supported only at the ends... A small boat just rides over one at a time...

[Snowpetrel]

Originally Posted by Neptune's Gear

The 30% rule is indeed the breaking crest height.
Wave height and length can break ships when they become supported only at the ends... A small boat just rides over one at a time...

https://youtu.be/pu4ogCy5d4k

Not sure how well you'd ride over the one at ten seconds... I understood the 30% rule was that a breaking wave with a height 30% of your LOA (or roughly equal to your beam) could capsize you if you are beam onto it, one 60% of LOA (or x2 beam) most likely will capsize you if you end up beam on to it.

[TeddyDiver]

Originally Posted by Snowpetrel

https://youtu.be/pu4ogCy5d4k

Not sure how well you'd ride over the one at ten seconds... I understood the 30% rule was that a breaking wave with a height 30% of your LOA (or roughly equal to your beam) could capsize you if you are beam onto it, one 60% of LOA (or x2 beam) most likely will capsize you if you end up beam on to it.

That's possible only if you're a "sitting duck" ie drifting sideways. In real life you are sailing and that adds a lot of dynamic stability.

Like on my last crossing from Azores to Ireland there was a gale for two or three days with wave heigh approximating 6m, highest 5% about 8m and uncommonly steep too considering their height.
What I did was steering the waves in the quarter and when seeing larger ones coming taking them more on the beam which effectively made the bow wave to break the incoming waves before hitting the boat resulting just spray or foam on decks and much less rolling compared to running. The boat was 65' so well in the 30% region.

Teddy

[Chas.7]

Originally Posted by Chas.7

Hello,
I was once in a storm off Diamond Shoals at Hatteras on a tender ship. The waves were like mountains, the ship’s propellers came out of the water. Once the helmsman lost control of the bow. I thought the ship was not going to right itself. It did, but the hull was cracked. We put in to Charleston making a 1/2 knot.
Chas

That ship was the FS411, a sister ship to the Pueblo. She had the same house design, its a two hatch coastal freighter with that modified house. I think it had a shallow draft. I was on a training mission but we seemed to followed the Russian fishing fleet.

[BillyPuffin]

I once saw the wave height buoy go past about 20m to port in the southern ocean. It's quite big to be honest. It was first I saw of it. It was the only thing we saw the whole way. Maybe should have the radar on in the day you think....?

[DumnMad]

Originally Posted by BillyPuffin

I once saw the wave height buoy go past about 20m to port in the southern ocean. It's quite big to be honest. It was first I saw of it. It was the only thing we saw the whole way. Maybe should have the radar on in the day you think....?

Hey, welcome to CF.

Pretty long odds I'd say. How many whales did you see ?

[Cheechako]

I've heard north of Vancouver Island they measure 100 ft with the sea bouy in wintertime...

[Neptune's Gear]

This is a good link;
Dangerous waves and your boat - Ocean Navigator - Ocean Voyager 2011

[BillyPuffin]

Originally Posted by DumnMad

Hey, welcome to CF.

Pretty long odds I'd say. How many whales did you see ?

Hundreds. Mostly in schools.

Except for one day about a half a mile off northern Tonga approaching from the east just after dawn (been waiting for light). Suddenly saw white water just dead ahead and we were running with the pole up. "Oh dear" I thought. Something like that. Then the 40' whale reappeared from behind the jib and landed just in front. Woke the kids up. Me that is.

[GordMay]

Greetings and welcome aboard the CF, Billy.