long period swell - do you guys ride in it?

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dom_moore

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i know from my limited personal experience that short fetch wind swell makes for a pretty miserable time in a motor boat, but what about the long range, propogated stuff? such as a 12 second plus wave interval clean swell unaffected by wind

at present my thoughts are that it would be quite a bit of fun and not really a threat to the craft right? on a following sea would you just sit behind the wave infront and chase it?

this is based on some hazy memories i have of chartering motor boats for offshore surfing in the fijian islands. just thinking of passages to scilly in light winds, but the seemingly omni present atlantic swell

so who goes out in this stuff? and have ye got any pics to share?
 
I go out in some pretty rough conditions if the waves are OK. What is important is not the wind or wind forecast, but the wave conditions at the time.

Short fetch is actually good inshore, as no appreciable waves build. It really depends on learning the local area, and the conditions that apply.

Offshore long waves are much easier than inshore chop, but there are so many conditions that apply, that there is no easy answer
 
[ QUOTE ]
so who goes out in this stuff? and have ye got any pics to share?

[/ QUOTE ] Dag Pike wrote a series of good books some years ago about rough weather handling which is worth a good read;

http://www.mhprofessional.com/product.php?cat=132&isbn=0071422099

http://www.amazon.co.uk/Power-Boats-Roug...TF8&s=books

They have been around for a while however the techniques still apply. The larger waves give you the chance to drive the boat around, up and down the waves, but in essence it takes practise and you wont always get it right. It is also very tiring constantly reading every wave so regular changes of crew are essential. On a recent delivery trip trom Brixham to Portsmouth we changed every 30 minutes. Boat preparation is essential as is route planning with "what if options" as well. (We had options to divert to Weymouth or Poole if the conditions became to much). Consider a couple of days of training as money well spent if your not sure.

Pete
 
It can be fun in a long swell, but the most comfortable ride is as you have said, just behind the top of the swell, but this then dictates your speed.
It also depend very much on the type of boat you are in, I have crossed the channel in a very underpowered 30ft boat that was going up the swell at 8 knots flat out and down the other side with minimal power at 18 knots.
 
Yes, you're right. In the same way that you can sit out back in big surf without getting your hair wet, if the boat length is small compared to the pitch of the wave then you just ride up and down it.

We crossed the channel this year in a brief spell of light winds but there must have been an atlantic depression, and there was probably a 3m swell, but very long pitch so barely noticed it.

I wouldn't say it actually adds to your enjoyment though, most mobos aren't really fast enough to use the wave faces for having fun. In theory i suppose you should be able to sit on the leading part of the wave and use small amounts of power to stay there and effectively surf it, but i haven't actually managed to do this in practice
 
I ve been in the North sea swells when two flybridge boats easily loose sight of one another in troughs including masts.

they are reasonably comfortable but it is not as easy as you suggest.

I cant think you will ever get to the scillies in troughs as the chances are they will be NW, W, SW and on your bow.

Even on the bow they are reasonably comfortable but you need to be careful as you leap off the crest .

A cruise speed of 20 knts is possible but it is more like 24 down and 10 by the time you climb to the crest, once at the crest a sharp turn on the wheel into the wave allows you to glide the stern quarter down the hill.
If you try to go straight off the top , the boat leaves the water and you slam down, as the wave is then down hill it is not nice.

From the lower helm the large swell is intimidating as wall after wall of water is above you like a Tsunami, all that happens is you just gently rise with the wave but you do not get to see the sky very often so best to be on the flybridge (Sunseeker offshore fine as you can look up as long as you are prepared to run with your covers off).

I have had boats with plenty of spare power ( top end 30knts) and still I have been down to 10-15 knts so I am not sure if they would be as comfortable if you didnt have the power to reach the crest ?

Following seas- they are moving in excess of 25 knts, I try to keep up as long as I can but they will undertake you so I dont think you could stay in the trough.

For emergency repairs I have run in one broadside on as they tend to be calm like the eye of a storm.



(When I say crest it is more of a hummock).
 
I have done this with very limited success.

Basically, using the right amount of power to stay on the wave. It is very tiring mind and can be dangerous when you get it wrong.

On a previous boat (a 39ft with twin 310hp engines on outdrives), I had a couple of mates with me and I was showing off my boat handling skills /forums/images/graemlins/laugh.gif. I managed to keep the boat on top of a wave for a good run - then lost concentration and went down the other side. This itself is not a problem but I got it wrong with the trim and the power and the wave picked me up at the stern and of course the bow dug into the back of the wave in front. Very close to broaching and frightened the (word removed) out of me /forums/images/graemlins/blush.gif

SV2
 
yep!

yes, but as you say we are talking long atlantic swells for the the boat to be going downhill for ten minutes or more at a time, and around uk these are only (or best) at far north in scotland and far south - away from protection of ireland.

Dangerous depends on wave shape and boat size. But long swell and biggish boat entirely safe, hardly any dangerof broaching and boat can plane at quite low speeds of 15knots, but tis all a bit weird and disorientating - I reached a harbour for fuel after about 200 miles of this off the coast of portugal, and the sea in the entire bay was on a slight tilt. Or it seemed like it anyway.

In shorter chop such as in the med, again downwind of course, and with highish 30knot winds you can see what's needed in terms of speed and almost exactly park the boat betwen two waves approx 35metres apart and moving at 15-20knots for quite some time (more than a minute anyway) but this gets a bit freaky cos the steering feel evporates (and mine not much kop anyway) with less water over the rudder.

You can pretty much do the same in a sailing boat altho the waves always overtake unless a racer. Otherwise, to avoid broach as slow waves come past i found the key thing was to ensure that weaherhelm eliminated eachtime if at all possible, that is to say the boat is returned to the downwind direction with steering pointing tinthat direction too, not a teensy bit off and this ain't easy at all cos it will tend to partly broach one way or tother. If a new wave arrivs and you haven't got control of steerig and steerig full over well then broach. The way i found was paddle/rip the rudder fast and repeatedly in short jerky moves fast one way slow back, to simulate the effect of water going over the rudder when actually it isn't. Or of course have engines so there is rudder control, and then use speed control to again get control of steering by altering relative speed
 
Re: yep!

thanks guys for all the replies there - that is one of the most informative threads i've had to a question i've submitted on any forum. no joke.

kind of as i had imagined. i am writing an article about origins of swell, and while digging around a bit the question popped into me 'ead.
 
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