If in doubt

[Martxer]

If in doubt got flat out was a term used in motocross racing and in certain situations was true, is this the same for motor boating?
As a novice to boating when out and about we are coming across areas of sea that look like water in a washing machine window.Currently we are slowing down to displacement speed. Question is do we keep taps open and skip over the top or carry on at displacement speed?
Thanks

 

[longjohnsilver]

If in doubt got flat out was a term used in motocross racing and in certain situations was true, is this the same for motor boating?
As a novice to boating when out and about we are coming across areas of sea that look like water in a washing machine window.Currently we are slowing down to displacement speed. Question is do we keep taps open and skip over the top or carry on at displacement speed?
Thanks

Depends on the size of your boat. 100’ stabilised super yacht, carry on at warp speed until it becomes too uncomfortable. For mere mortals like me, if there’s too much crashing and banging then slow down. Find a speed that suits your boat, crew and the conditions.

 

[BruceK]

Displacement speed in a planing boat in rough water is going to roll and pitch more violently with a greater chance of stuffing in the bow while going full tilt and slamming can damage the boat. As above find a mean whereby the boat is most comfortable for the conditions. This sometimes is in no man's land when you are neither planing nor in full displacement mode. For example on my planing boat going 14 knts will handle most of what the Irish sea can throw at it, albeit the supercharger whine can get annoying.

here are two extremes taken on the same day (ignore time stamp of upload)

displacement - too slow

Balls to the wall - too fast

14 knts. Goldilocks albeit with SC whine (taken at a different date in similar conditions)

 

[Portofino]

If in doubt got flat out was a term used in motocross racing and in certain situations was true, is this the same for motor boating?
As a novice to boating when out and about we are coming across areas of sea that look like water in a washing machine window.Currently we are slowing down to displacement speed. Question is do we keep taps open and skip over the top or carry on at displacement speed?
Thanks

Depends on the hull form .
Deep deadrise s over 20 degrees and fine entries do not actually as you say “ skip over the top “ .So no “crash and banging “ to quote LJS .
The sea parts .If there is any air , because of the deep V it lands “ comfortably “ to quote LJS .
Sounds like you have already committed to purchase anyhow .
Take a look at Mr Googlers new tool , it won’t disappoint ride wise .
Consequently we never are unable to plane and let rip waves with a 23 degree deadrise .In fact arguably in some instances actually going faster = smoother ride .

So why do they boat builders do it ? Adopt low a dead-rise ?
Requires less Hp , smaller engines after placed aft freeing up more cabin space .The flatter the aft sections the less power is needed to get up and plane .Less drag and more inherent vertical lift .

Moving on to charging / flattening a head sea the centre of gravity in relation to centre of lift plays a big role .
You ideally want the those two to be as close as possible , to minimise any rotation, pivoting between the two .To do that you need centrally placed engines , which eats interior cabin volume .A deeper V means you can also lower the centre of gravity placing triangle shaped tanks in the bottom of the V .
A lower centre of gravity means less pitching , which means more finer forward entry to begin slicing the next wave apart to pass .
Hence no “ skipping over “ and “crashing “ .
You need to lay down a lot of Hp through big pitched props to power the hull through.

Its a sum of many parts , all the parts not just odd one or two .

There is no black art or mystery to it .
A good read is this book - The naval architecture of planning hulls by Lindsay Lord .
Its all in there .

So if you were growing roses a white and red and were asking why when cross pollinating in the green house you got pink ( or did not get pink ? ) Or asking why birds have different shaped beaks , I would refer to this book The Origin of species by Charles Darwin .

There is no luck or chance involved in boat hull design and there seaworthy ness in waves at speed .

 

[Martxer]

Thanks for the replies guys I will give those suggestions a whirl next time . ?

 

[Portofino]

You might find this informative?

 

[LBRodders]

You might find this informative?

has @Mr Googler got crew?

 

[Mr Googler]

They’d go straight over the side if they wittered on like that all the time ???

watch any of these too!

 

[LBRodders]

They’d go straight over the side if they wittered on like that all the time ???

what any of these too!

Funnily enough, the chap in the small white and blue boat nailed it. Experience conquers all!

 

[Kawasaki]

Rode 'Motocross' at a fairly serious level when suspension travel was not what it is now!
So when new to boating and starting off with planing hulls I tried various 'riding' styles
Like trying the 'if in doubt' approach etc
In some ways you can relate to MX and blatting over the 'whoop de doos'
Its OK on a 'Track' the lumps stay relatively the same each lap so can kinda work out what yer gonna do
Problem is the sea aint so predictable and the 'circuit' changes rapidly before your very eyes
Like the motorbike its all about throttle control and reading ahead
If you spot a flat bit, 'Blat it' then back off just before and 'wheelie' over it gently kinda
A planing hull is a planing hull but as mentioned there are differences in hull form and weight etc etc
Compare a proper enduro machine with an out and out Motorcrosser
Do the same thing in a different way
It really is about throttle control and looking ahead and guessing what the 'F' is going on!!!
Getting used to the Boat and practicing in different sea states

 

[Mr Googler]

The orange Sealine at the end rolled around like a cork……..I can see why Marina Queen stays ……..in the marina

 

[Portofino]

Funnily enough, the chap in the small white and blue boat nailed it. Experience conquers all!

Two different comparisons. Those going out effectively up wind head on and that guy you refer to ( the Lekker ) + the Cabo sport fisher surfing back in effectively on a down wind run sat very comfortably on one wave .

The “ top gun “ and “Cigarette “ ( going out - up wind ) came unstuck due to too much speed and importantly when airborne far too much rearward weight .
See them immediately drop at the stern , or adopt a bow pointing to the sky as soon as the hull was out of the water .= massive slam .
But as I say it’s so easy with sterndrive s to paper over the weight distribution cracks . When designing boats .
They are kinda stuck because that’s how it is .
Having said that some Arnesons boats are on Jack shafts ......moving the lumps fwds to mitigate somewhat the weight distribution.

I have mentioned this before knowing the seas in the Med more than happy to race with my boat Cannes to Corsica 10 x laps with theses sterndrive cigarette s .Because I know it will only be pancake flat for 10-20% of the distance .
In the med they only come out to play in dead pan seas .

 

[LBRodders]

Two different comparisons. Those going out effectively up wind head on and that guy you refer to ( the Lekker ) + the Cabo sport fisher surfing back in effectively on a down wind run sat very comfortably on one wave .

The “ top gun “ and “Cigarette “ ( going out - up wind ) came unstuck due to too much speed and importantly when airborne far too much rearward weight .
See them immediately drop at the stern , or adopt a bow pointing to the sky as soon as the hull was out of the water .= massive slam .
But as I say it’s so easy with sterndrive s to paper over the weight distribution cracks . When designing boats .
They are kinda stuck because that’s how it is .
Having said that some Arnesons boats are on Jack shafts ......moving the lumps fwds to mitigate somewhat the weight distribution.

I have mentioned this before knowing the seas in the Med more than happy to race with my boat Cannes to Corsica 10 x laps with theses sterndrive cigarette s .Because I know it will only be pancake flat for 10-20% of the distance .
In the med they only come out to play in dead pan seas .

Yes. one has to assume that as he got in - he got out!

 

[LBRodders]

The orange Sealine at the end rolled around like a cork……..I can see why Marina Queen stays ……..in the marina

He wouldn't be able to keep the carling in the can and off his white vest.

 

[julians]

They’d go straight over the side if they wittered on like that all the time ???

what any of these too!

Looks like a lot of those "go fast" boats in that vid could do with using the engine trim and trim tabs to lower the bow into the waves a bit more, they look way too bow up for those conditions

 

[LBRodders]

An example of where slow or 'fast' just doesn't work for the boat. I had to bottle it and go inshore quartering.

@ 2m 55s

 

[Martxer]

Top gun is a fine example when going flat out is not the best option and am guessing the orange sea line too slow ?

 

[James L]

I find every day is different, but conditions are very changeable here.
Try speeding up and see how it goes, no matter what boat you have going faster will work up to a point.
At some point regardless of hull shape or weight you will end up with air under your hull and then you're going too fast for the conditions.
A deep v hull will handle it better than a flatter shaped hull, but unless you are properly stowing everything every time you set off anywhere you're better off easing off and slowing down a bit.
Sometimes I will think I have it all sorted, making good progress without much bashing and just a bit of white water spraying over the boat and as I come off the top of a wave I find a huge boat sized hole on the back of it and we get a good pounding. It's all just part of the learning curve.

 

[Martxer]

Rode 'Motocross' at a fairly serious level when suspension travel was not what it is now!
So when new to boating and starting off with planing hulls I tried various 'riding' styles
Like trying the 'if in doubt' approach etc
In some ways you can relate to MX and blatting over the 'whoop de doos'
Its OK on a 'Track' the lumps stay relatively the same each lap so can kinda work out what yer gonna do
Problem is the sea aint so predictable and the 'circuit' changes rapidly before your very eyes
Like the motorbike its all about throttle control and reading ahead
If you spot a flat bit, 'Blat it' then back off just before and 'wheelie' over it gently kinda
A planing hull is a planing hull but as mentioned there are differences in hull form and weight etc etc
Compare a proper enduro machine with an out and out Motorcrosser
Do the same thing in a different way
It really is about throttle control and looking ahead and guessing what the 'F' is going on!!!
Getting used to the Boat and practicing in different sea states

Something like this? Redirect Notice

 

[julians]

At some point regardless of hull shape or weight you will end up with air under your hull and then you're going too fast just right for the conditions.

Fixed that for you!