WEATHER AND SWELL LESSON REQUIRED

[spaners]

Hi all.Im after some tips on understanding the relationship between wind and swell.

I have a Allycraft 4.75 which I am used to coming out from Box Head and venturing up the coast 5klm or so and out about 2klm on what I think are going to be good days.This summer I would like to try and get to the Fads or further on a good day but at the moment I am not to sure what a good day will be going that far out.For example would it be best on a easterly swell with easterly winds or westerly winds,southern swell with easterly winds,n/east swell with southerly winds.At the moment if its under 1mtr swell and 10knt I will give it a go,But I don't want to "give it a go"if Im going out to the Fads.

Thanks in advance...Tight lines and may your knot's hold..

[Twinfisher 4.9]

Hi Whiting, this is the challenge that we all face every day when we are planning on venturing out. No easy answer but checking all of the popular weather websites especially those featured on this site, is a good start. To me the major factor, apart from the obvious forecast that rules it out in the first place, I look at is what is going to happen later in the day when I'm likely to be heading home. A lot of this only comes from experience and this only comes with time on the water and some unpleasant trips back. Whilst your boat isn't that large it should be fine for the FAD's in the right conditions. Heading back into a 20 knot westerly from offshore is not going to be pleasant. There is no easy answer, but when you go out, keep you radio on and regularly check the latest forecast.

[brickman]

i have a 5 meter cuddy cab savage scorpion and this is how it has to be for me to head out also i have clears and a bimini

swell max 1.5

wind 10kn or less

wave pulse 8 second but more is better

note it can all change in seconds and i never head out if there is bad weather coming from the west a change in the wind can chop it up real quick

if the wind is going to be over 15kn at say 12.00pm i'm in or close to being in by 11.00 hope this helps and i'm shore more people will add to this cheers gary

[arpie]

Same advice I give to my yakking buddies .........

If in doubt - DON'T GO OUT!! Other people's lives may be put at risk if you go out in conditions that you are not familiar with - and they have to go out to save you!

cheers

Roberta

Edited October 23, 2013 by Roberta

[tasksta]

Agree with all this good info. Also safety gear is a bo brainer and know how to use it. I have another personal rule that i come back in close by 12pm no matter what the weather. I have seen it change too many times and always around midday. Just from my personal experience. My boat is 4.90 and was at the first FAD last week. Also a southerly is NEVEr good if you see it forecast get in ATLEAST two hours early and stick to yhe 12pm rule!

Hope this helps

[Flickn Mad]

Mate we have been 15 mile out in 3m swell in a tiny. but due to a steady 5 to 10 not norwester no chop to contend with. back at the ramp by 11am. eating a pie at 12 30 watching every man and his do trying to out run a 30 knot soueaster from the headland.

you want to see a good pattern of weather and not just a window when going wide in small boats.

[Nolongeramember]

I would like to know aswell, the relationship between the swell direction and wind direction and how together they affect the chop produced. For example, if the wind is going the same direction as the swell is that better than the wind going against the swell? Or, is the wind going parallel to the swell better?

I do know from experience, that a southerly wind can produce bad conditions even with a low speed wind. But Ive been out other times with a southerly blowing even harder with the same swell height and the conditions were not as bad so there has to be more to overall conditions than just swell height and wind speed.

[Testlab]

The rule of thumb for wind and swell is you get 1m of swell for every 10kts of wind, where the wind has been been blowing across the ocean for quite some distance. So a 20kt sou'easter will bring up a 2m SE swell.

On top of the swell you get the "sea" which is the effect of the local wind. So a 1m swell with a 0.5m sea means 1.5m. This is called the combined sea state.

Whenever you read a weather report containing wave heights it is important to remember these are an average, be prepared to meet waves up to twice that height !!!!!!!! This is why you must know your vessel limits because you may be able to handle 1m seas peaking at 2m but can you survive 2m seas peaking at 4m.

How often does this happen? All the time !!!! This is what led to the total loss of a 6.0m long vessel off Long Reef last year in seas around 1.5m when they were suddenly confronted with a set of four 4m waves that went straight over the nose green and filled it completely. The vessel rolled over in less than 20 secs, and this was a 2C commercially built vessel.

So how can you tell what is safe? Local knowledge goes a long way. Know the area you are going and don't just rely on forecasts. I am from the Central Coast too and regularly venture off shore and throughout the Hawkesbury, up to Port Stephens and down to Sydney. One of the worst places to be caught is in Broken Bay, on a runout tide, with a NE-SE swell and the 20kt summer NE that comes up most afternoons. The waves are fast, short in period and steep on the approaching face. There are also reflections from Barrenjoey, West Head and Lion Island. With a 1m swell it's uncomfortable in a 5m boat, above 1.5m it's "interesting" and damn scary when the bigger sets roll in.

Coming back in around Box Head from the north can get very uncomfortable when the swell and tide are conducive to bouncing waves back off the SE facing headlands when the swell is from the S around to ENE. These seas can suddenly leap up in front of you at twice the height of those nearby. In a southerly blow it becomes treacherous so plan to be home at least 2 hours before the predicted arrival of a southerly change.

If you can see tall, wide spread clouds in the distance tothe south then watch them carefully. If you see them move toward you or they grow bigger in say 10 mins then pack it up and get home. A southerly storm front 20 miles away (say in Sydney) and you're 2nm off third point will be on you in around 45 mins and as little as 30 mins. At 20 kts it will take you 30 mins to get back inside and around half tide rocks assuming a 1m sea and an average boat.

How your boat handles the conditions depends on its size, type and especially loading and weight distribution. Be conservative.

When making a go/no-go decision check the forecasts and use every tool available. Check the tides and the tide heights to work out if you can get back across bars or if the speed of the tide will be worsening the prevailing wind waves and swell. Look at the wind-wave forecast interactive maps on the BOM website. Be conservative and leave early to make the run home.

A wind blowing from the west will soften a swell coming from the east but the chop may be unpleasant on the return journey. An easterly wind on an easterly swell and a run out tide will mean bigger steeper waves and when running to the west (coming home) you have to be careful not to dive over the front of the steepest waves.

In general, head out early as conditions will be calmer most days. Come home early if heading outside and spend a few hours on enclosed waters to round out the day or go home for a beer and a feed.

Finally, call Marine Rescue Sydney on VHF 16 (or VHF 22 or VHF 81 if they don't answer/hear you on 16) with your trip details. If you only have 27MHz then call on Ch 88 (27.880MHz) but VHF will give you much better coverage. Don't forget to log off afterwards and if you think you may wind up in trouble call for help THEN not when you're 5 mins from piling up on the rocks or just about to sink.

Hope this helps.

[Don_]

The rule of thumb for wind and swell is you get 1m of swell for every 10kts of wind, where the wind has been been blowing across the ocean for quite some distance. So a 20kt sou'easter will bring up a 2m SE swell.

On top of the swell you get the "sea" which is the effect of the local wind. So a 1m swell with a 0.5m sea means 1.5m. This is called the combined sea state.

Whenever you read a weather report containing wave heights it is important to remember these are an average, be prepared to meet waves up to twice that height !!!!!!!! This is why you must know your vessel limits because you may be able to handle 1m seas peaking at 2m but can you survive 2m seas peaking at 4m.

How often does this happen? All the time !!!! This is what led to the total loss of a 6.0m long vessel off Long Reef last year in seas around 1.5m when they were suddenly confronted with a set of four 4m waves that went straight over the nose green and filled it completely. The vessel rolled over in less than 20 secs, and this was a 2C commercially built vessel.

So how can you tell what is safe? Local knowledge goes a long way. Know the area you are going and don't just rely on forecasts. I am from the Central Coast too and regularly venture off shore and throughout the Hawkesbury, up to Port Stephens and down to Sydney. One of the worst places to be caught is in Broken Bay, on a runout tide, with a NE-SE swell and the 20kt summer NE that comes up most afternoons. The waves are fast, short in period and steep on the approaching face. There are also reflections from Barrenjoey, West Head and Lion Island. With a 1m swell it's uncomfortable in a 5m boat, above 1.5m it's "interesting" and damn scary when the bigger sets roll in.

Coming back in around Box Head from the north can get very uncomfortable when the swell and tide are conducive to bouncing waves back off the SE facing headlands when the swell is from the S around to ENE. These seas can suddenly leap up in front of you at twice the height of those nearby. In a southerly blow it becomes treacherous so plan to be home at least 2 hours before the predicted arrival of a southerly change.

If you can see tall, wide spread clouds in the distance tothe south then watch them carefully. If you see them move toward you or they grow bigger in say 10 mins then pack it up and get home. A southerly storm front 20 miles away (say in Sydney) and you're 2nm off third point will be on you in around 45 mins and as little as 30 mins. At 20 kts it will take you 30 mins to get back inside and around half tide rocks assuming a 1m sea and an average boat.

How your boat handles the conditions depends on its size, type and especially loading and weight distribution. Be conservative.

When making a go/no-go decision check the forecasts and use every tool available. Check the tides and the tide heights to work out if you can get back across bars or if the speed of the tide will be worsening the prevailing wind waves and swell. Look at the wind-wave forecast interactive maps on the BOM website. Be conservative and leave early to make the run home.

A wind blowing from the west will soften a swell coming from the east but the chop may be unpleasant on the return journey. An easterly wind on an easterly swell and a run out tide will mean bigger steeper waves and when running to the west (coming home) you have to be careful not to dive over the front of the steepest waves.

In general, head out early as conditions will be calmer most days. Come home early if heading outside and spend a few hours on enclosed waters to round out the day or go home for a beer and a feed.

Finally, call Marine Rescue Sydney on VHF 16 (or VHF 22 or VHF 81 if they don't answer/hear you on 16) with your trip details. If you only have 27MHz then call on Ch 88 (27.880MHz) but VHF will give you much better coverage. Don't forget to log off afterwards and if you think you may wind up in trouble call for help THEN not when you're 5 mins from piling up on the rocks or just about to sink.

Hope this helps.

Thanks a lot for that info! I'm sure a lot of people will find that very useful..

[Guest mike2153]

General rule of thumb for me goin into the harbour and just outside the heads in my 4.eyte runabout 1.5 swell more than 10knot winds don't bother.

[spaners]

Thanks for all the help chaps.

Tight lines.

[Flickn Mad]

I hope you got some good info here mate.

I went out Friday around north head, forcast low wind and swell and small chop,

Wind was up early and with some sets coming in over 2m and a uncomfortable chop bouncing back of the rocks made it interesting.

The swell height itself I don't worry too much about unless your crossing a bar but swell frequency/pulse is more a factor for me.

no swell with big sea is more a concern.

At the end of the day you need to find your own limits.

Take on board what the guys here have to say, there is a wealth of knowledge you can tap into.