This is not a troll.

Slow_boat

Slow_boat

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I was wondering;

Back in the 70's I was doing a bit of powerboating. It was accepted that in anything but a flat calm sea a planing boat had to throttle back or be damned uncomfortable, if not hazerdous. Is that still the case or has some gizmo been invented that means you can keep the throttles open for longer?
 
I think that back then there were very few deep vee type motor cruisers around - nowadays there are many more, of all types, and motor boat design has advanced a lot in the meantime.

Many of the motor cruisers of the early 70's had very shallow vee hulls, and were perhaps more suited for calm water cruising rather than offshore.

Hull design has advanced a fair bit since then, with more deadrise forward, and other subtle changes to improve the ride and comfort.
Hence why you see a lot more powerboats going fast in relatively (compared to 30 years ago) choppy conditions.
Basically, the deeper the 'vee' of the hull, the softer the ride (all else being equal).
 
Our preferred cruise speed is 25/26 but has to be flat calm.

24 is the usual speed.

When the waves get larger we reduce to 20

If I need to reduce to 17/18 it is bad and family start to moan, at this point I head for a safe haven.

Now bearing in mind I m heading for the safe haven at 17 or if I have done my job right then my safe haven will be with the waves so 19/20 knts

ALWAYS/ALWAYS the Yachts are in port first with their sleeping bags and wet weather gear drying.............conclusion Yachts head for shelter first and possible several hours earlier in conditions we were happy to set off in.

Family crews frequently come on board to check the weather on our PC, all male crews tend to be storm bound longer as they are reluctant to seek advice from a stinker, I just hope I never put any family boats off with a wrong call as I often only need a 6 hour window with wind with swell.

That is

I will frequently punch the tide at 24knts in preference to getting hammered at 19knts wind against swell.
 
I guess you just need the right boat.....:-)

Also I find it makes a difference which way your heading, into wind can be hugely different to a following sea, I tend to take it gently on the old girl, I wont head into more than a four, but came home from Weymouth in September with a Seven behind us.
 
Big changes since that Bernard Olsinki guy came along. Planing boat can not mosey along quite happily in big sea, at maybe 8 knots and smaller ones at maybe 18 knots, in following seas, some can just blam along regardles, up to a F7 or so. Much depends on the direction of the sea and type of waves. Big seas being wurprisingly easy to bomb over. Solent chop, just a pain in the arse.
 
Nowadays I think that it is often a case of the fast motor boat can take more punishment than her crew can - this is certainly the case with the RNLI fast offshore lifeboats.
I went out on trials once on the prototype (FAB 3) of the 17m. Severn class. The Cox'n was basically told to try his best to give her as much grief as possible - so we were doing 25 knots off Poole Harbour into a F 7 and waves probably about 2m high, and she was easily coping with the conditions.
The crew however all needed their seat belts on so as to not hit their heads on the roof with the G forces experienced as she came off the waves.
 
He was indeed born in Norfolk at Burnham Thorpe, but the first time he stood on a deck was when he joined the Navy at the age of 12.

According to one pilot book describing the entrance to Burnham Thorpe had he ever tried to sail out of the place he would undoubtedly have joined the army!
 
I thought as I wrote it... 'I bet... nah... no one will...' You probably know Nelson's father was a rural vicar. Recreational sailing was as likely in 1760s Norfolk as mountaineering. There's no evidence that Nelson could sail before he went to sea. Instead he made up for it after he got there, and once wrote to his father complaining he hadn't set foot on land for two years. I'm not a Nelson expert but I do keep a copy of his correspondence on the boat (7 volumes), not least as a nice surprise for any French Douanes who treat me to a rummage.

As for waters on the Wash; with a N or NW wind above 4 and the tide going in either direction (one way it's breaking on shallows, the other it's wind over tide), going round that blinking corner from Cromer is about as miserable as it's possible to be on a boat.
 
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Or the Solent

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Re: Some thoughts re engines

I mentioned this thread to a friend who has a keen interest in all aspects of design and construction of power boats, and he noted that nobody had really mentioned the enormous developments that have happened with engines in recent years.

He sent me an email (copied below) with the following thoughts, which I think are very relevant - I was mentioning the effect of hull form in a post above, but of course there is a lot more than just hull design involved here re the quest for speed.

My friend said :

This is an interesting question, and worth a book in itself! But I feel, that it's nothing to do with hull shape - but engine design and improvement - mainly the introduction of the 'lightweight' (sic) high-speed (turbo?) diesel.

Designers of old knew about deep, and V, shaped hulls (as per in some of Uffa's pre-war books). Indeed in his 4th book he shows the lines of two high-speed German powerboats (that were developed into the Schnel-boats/E-boats).

It's like the Nelson-hull question - everyone thinks they were the first semi-displacement craft able to go out into a seaway, and keep going... but only narrow-minded Brits think this; what about the American Lobster boats, the commuter boats, and the Down-easters?

And earlier still, the German Schnell-boats. My Dad was in MTBs from 1936 to 1942 (these craft were a flat bottomed, chined design, using x3 1650 hp Isotta petrol engines). They used to look on in envy at E-boats with their round-bilged, deep (sort of), hulls and high-speed Mercedes diesels - and an E-boat could go just about as fast as a early Vosper 70 footer in calm water... In a seaway, they were far more comfortable (and unfortunately a better firing platform!).

No, most designers knew that with low power engines, the only hope of speed was a flat planing hull (and put up with the slamming) to get simple lift, and that only big engines could pull a deep-V up onto the plane. But there were very few engines available then.

It's worth bearing in mind that diesels 40 - 50 years ago were slow turning and heavy (see Kelvin, Lister, etc), heavyweight chuggers with enormous flywheels; they were designed for continuous running rather than maximum power output. It was not until about the mid 60's did 'high-speed' marine diesels, as they were called, start to come about.
That is, these were marine diesels that would rev above about 1,400 rpm and produce lots of power; and could be used to turn propellers at speed.

Of course there were petrol engines out there as noted above re the MTBs (and others), and these were more successful.
But they were still very heavy; they only revved to about 4,000 rpm max if race tuned, and were not stunningly powerful as we now know it.
They used SAE output ratings - ie everything stripped off the engine to give a bhp figure, as opposed to today's DIN rating which includes every power-sapping ancillary fitted.
Some of the Garr Wood American designs were deeper V, and slammed a lot less than British hydroplanes; but some of them weren't so fast, just a lot more 'seaworthy'.

The turbo-charger (I think), in the 1960's and 1970's transformed the diesel, allowing it to rev a bit more, and it started getting placed in powerboats by clever designers. Especially when these engines started shedding some weight. A decent engine started to allow a deeper V hull to get some speed up, and even plane - by the time of the Fairey Huntresses et al... But we all know that one definition of a boat is: "a compromise".
So a Deep-V means less space in the hull, and a requirement for more (uneconomical) power.
Hence some of the clever 'Modified-V' hulls, or as the Americans sometimes call them variable-vee hulls.
Bernard Olesinski was very clever with these... but he had the engines....... .
 
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