What factors affect ride comfort on the water?

[wipe_out]

Just wondering what factors effect the comfort of the ride on the water when the conditions aren't smooth..

Our 25ft, like all boats is brilliant in flat water but as soon as the swell starts picking up and it gets a bit choppy it quickly becomes quite uncomfortable.. You can go slowly in which case there is lots of pitching and rolling or faster and there is lots of slamming.. This maybe a characteristic of our hull in particular of course..

In order of best ride to worst how would you rate displacement, semi-displacement or planing hulls as the water gets rougher? (obviously there is more to this question because of the speeds that each hull operates at)

Does the size/weight of the boat have a significant effect? So would a 28ft be much better then a 25ft and a 30ft much better than a 28ft or would you have to go from say a 25ft to a 40ft for the size/weight to be a large factor in the ride?

Or is the single biggest factor the specific hull design? Have they changed much in the last few decades?

 

[omega2]

You do not say what boat you are driving?? but the big chrome lever on your right has a lot to do with slamming.

 

[wipe_out]

You do not say what boat you are driving?? but the big chrome lever on your right has a lot to do with slamming.

I'm on a Larson Cabrio 254.. Just over 25ft, single petrol engine.. Nothing fancy at all..

Yes, I know the speed is directly proportional to the level of slamming.. The lack of speed is directly proportional to the rocking and rolling..

Just interested in what to look for in my "next" boat that will give a more comfortable ride to all on board since the water is more often not completely smooth..

 

[Kawasaki]

Semi Displacment gives you a good compromise for comfort and velocity!
With your type of boat when it gets choppy your only 'tools' to help are the throtlle lever and trim
Typacilly a planing hull of that type/size is comfy up to eight knots ish and then 'akward' until 16 ish when getting up on the plane
So in a chop you are normally quite actice using said 'tools'!

 

[omega2]

Just had a look at the Larson, yes it is full on planer, and in a slop I fear it will be a handfull, however if you use as advised by Kwaka you should be ok. All boats rock and roll when the going gets tough, staying in them is the secret LOL

Semi's are generally at their best from 30ft upwards. It's the admiralty formula that kicks in i.e overall length = 3 beam but do not expect to be completely free of movement even then.

 

[wipe_out]

Typacilly a planing hull of that type/size is comfy up to eight knots ish and then 'akward' until 16 ish when getting up on the plane

Awkward is an understatement.. You should have seen the looks on the some of the faces yesterday when I tried to get up a bit of speed to power through it more quickly.. I think panic was about to set in for those that aren't used to boats at all..

I am pretty sure this boat is about the worst for bad sea conditions.. I'm already thinking about something bigger in a year or two to be used for going quite a lot further as well.. As far as size goes I am probably thinking a 10-15 year old mid 30 footer, maybe at a stretch an older 40ft..

 

[CaptainMike1970]

I think that there are 4 main factors to consider

1) skill of the helm, consider a day of own boat tuition to get the best out of what you have got, a good instructor will help you use the throttle and trim to get the best from the engine/hull combination plus give you tips on how to approach and deal with the waves and look for the smooth path.

2) dead rise, how deep is you "V" the deeper the softer the ride in the rough stuff (if we are talking planing boats) but you also need the power in the engines to make the most of it!

3) length, longer is generally better! If you are out in the Solent, the nasty Solent chop is a lot easier to deal with if you have a few extra feet on the hull length

4) weight, usually a function of length but a bit more weight and you get bounced around less and can knock the tops off the waves.

Just my thoughts but I'd start with some own boat tuition before chopping the boat in!

 

[crazy4557]

My first boat was a Rinker 27' and that slammed in anything more than a flattish sea. Slowing down helps but such a comparatively light weight and typical American sports cruiser hull design means you will always be liable to the odd slam or three.
I moved to a Targa 31 which was much better, it's a bigger heavier hull but it still slammed quite a lot in medium sized sea's. had a horrible journey across Lyme bay once with biggish seas and she slammed a lot then despite slowing right down!
Next was a 40' Sealine and that meant almost no slamming and a much more smooth ride.
So, you really need to get to at least 40' for almost no slamming or 30+ ft for a reasonable slam free ride in average sea conditions.
I ended up with a 46' fly bridge and you still get the odd slam but that is only in rough water otherwise it just ploughed through anything.
Hope this helps.

 

[Portofino]

Or is the single biggest factor the specific hull design? Have they changed much in the last few decades?Qoute Wipe- out
Yes I think it's
Slamming is because the hull has lifted out of the water and basically bouncing on top from wave to wave as opposed to cutting through the waves .
Reducing speed causes it to drop back or drop off the plane- no good then you roll and pitch as you say .
For a given length go For a hull with a deeper V particulary at the bow ,so it can cut through and if poss at the stern .
Prob is to get lift designers will tend to flatten the stern 1/3 rd .Thus is because without the flatter aft sections for a given HP one can not get lift .To overcome this they can fit bigger more powerful engines and/ or increase the beam .
More beam = more likelihood of slamming .
So look out for a norrow beam, deep V powerfully engined boat eg an old Sunseeker Tomahawk, Superhawk, Thunderhawk,and some Windys ( norrow beams to go through Scandinavian locks) The compromise is of course less accommodation .
All things being equal look out for the ones with the deepest V both bow and stern area,s when you are ready to change.
One more thing to reduce slamming in other words travel faster in a planning boat in a big head sea - adjust the trim tabs down to push the bow ie the V down to cut through and push water aside as opposed to the boat trying to lift over the wave ,once agian HP is king .

 

[MapisM]

Or is the single biggest factor the specific hull design? Have they changed much in the last few decades?

In a sense, yes it is.
And nope, they didn't change that much, in spite of the claims you might read from some builders.

But it's worth mentioning that the single biggest factor is not the hull design ALONE.
It's the fact that the hull design implies other choices.
You will never find a full displacement hull without a deep keel, a substantial weight, stabilizers (at least on biggish boats), etc.
And by the same toke, you all P hulls are designed to be light, with low draft/drag, etc.

But all that said, THE factor which affects ride comfort on the water remains the sea.
As a friend of mine used to put it, the sea is rough - period. When it's calm, it's an exception.
Pleasure boating is all about exploiting these exceptions!

 

[hlb]

Or is the single biggest factor the specific hull design? Have they changed much in the last few decades?Qoute Wipe- out
Yes I think it's
Slamming is because the hull has lifted out of the water and basically bouncing on top from wave to wave as opposed to cutting through the waves .
Reducing speed causes it to drop back or drop off the plane- no good then you roll and pitch as you say .
For a given length go For a hull with a deeper V particulary at the bow ,so it can cut through and if poss at the stern .
Prob is to get lift designers will tend to flatten the stern 1/3 rd .Thus is because without the flatter aft sections for a given HP one can not get lift .To overcome this they can fit bigger more powerful engines and/ or increase the beam .
More beam = more likelihood of slamming .
So look out for a norrow beam, deep V powerfully engined boat eg an old Sunseeker Tomahawk, Superhawk, Thunderhawk,and some Windys ( norrow beams to go through Scandinavian locks) The compromise is of course less accommodation .
All things being equal look out for the ones with the deepest V both bow and stern area,s when you are ready to change.
One more thing to reduce slamming in other words travel faster in a planning boat in a big head sea - adjust the trim tabs down to push the bow ie the V down to cut through and push water aside as opposed to the boat trying to lift over the wave ,once agian HP is king .

The problem with your design is, that where as it might be OK in a head on sea, it will be positively dangerous in a following sea. If you look at the legendary Bernard Olsinki ?? design of the eighties, which revolutionised boat design for the foreseeable future, it is the absolute of your design.

Whist head sees are un comfy, following seas can be dangerous, so a boat that first deals with that problem is the best start.

Avoid outboards or outdrives, if you want a good sea boat, the props don't help a lot if spinning in the air.

Having said all that, bigger is better, 35ft will cope with most anything if the hull is right.

There is no advice that can be given here as all seas are different, but a lot of the time I found 10 knots a good speed in very rough seas, as the boat seemed to glue it's self down and push the water away, slower and it would begin to roll. Mind it was about the most expensive speed.

 

[dpb]

We have recently moved from a 21 fter to a 31 fter, and the difference is huge, ......it means Mrs DPB can drink her wine instead of wearing it!!
All our previous boats were 25ft or less and they all rode virtually slam free if kept on the plane at 17 to 19mph....but you still got chucked about a bit!

 

[Portofino]

The problem with your design is, that where as it might be OK in a head on sea, it will be positively dangerous in a following sea. If you look at the legendary Bernard Olsinki ?? design of the eighties, which revolutionised boat design for the foreseeable future, it is the absolute of your design.

Whist head sees are un comfy, following seas can be dangerous, so a boat that first deals with that problem is the best start.

Avoid outboards or outdrives, if you want a good sea boat, the props don't help a lot if spinning in the air.

Having said all that, bigger is better, 35ft will cope with most anything if the hull is right.

There is no advice that can be given here as all seas are different, but a lot of the time I found 10 knots a good speed in very rough seas, as the boat seemed to glue it's self down and push the water away, slower and it would begin to roll. Mind it was about the most expensive speed.

The bow flare is deliberate ,it's a 7 inch flare each side of the point to prevent it digging in or being " positive
Y dangerous"
http://www.google.co.uk/url?sa=t&rc...ctAplDnbCjiZ3S0KA&sig2=Lg7_VMJugdKPlL09BL0x9A

 

[rbcoomer]

The bow flare is deliberate ,it's a 7 inch flare each side of the point to prevent it digging in or being " positive
Y dangerous"
http://www.google.co.uk/url?sa=t&rct=j&q=sunseeker+xs2000&source=web&cd=1&ved=0CDAQtwIwAA&url=http%3A%2F%2Fwww.youtube.com%2Fwatch%3Fv%3DnGksOnmX_xs&ei=ZKmjUZKoD9GU7Qa6qIDgAQ&usg=AFQjCNHWVbZ6P7fPWctAplDnbCjiZ3S0KA&sig2=Lg7_VMJugdKPlL09BL0x9A

Fantastic video and truly beautiful boat! If only my pockets were deeper...

 

[hlb]

The bow flare is deliberate ,it's a 7 inch flare each side of the point to prevent it digging in or being " positive
Y dangerous"
http://www.google.co.uk/url?sa=t&rc...ctAplDnbCjiZ3S0KA&sig2=Lg7_VMJugdKPlL09BL0x9A

Yep, it's slamming like buggery, perhaps what's wanted in a high speed boat, that wont be allowed out in rough stuff.

Notice the predator is designed completely different.

 

[Portofino]

Yep, it's slamming like buggery, perhaps what's wanted in a high speed boat, that wont be allowed out in rough stuff.

Notice the predator is designed completely different.

They can Allways throttle back from 70 knots in the XS2000
If the entry is soft - like when it's takes off 3/4 of the way in ,then that is not slamming .
Merely illustrating the deep V component and norrow beam of the equation
This one below is even faster 108 mph ,but you Pootle at 40-50 knots

http://www.google.co.uk/url?sa=t&rc...=1fTkppRr8ga5oeGokmgj_w&bvm=bv.47008514,d.d2k

 

[hlb]

They can Allways throttle back from 70 knots in the XS2000
If the entry is soft - like when it's takes off 3/4 of the way in ,then that is not slamming .
Merely illustrating the deep V component and norrow beam of the equation
This one below is even faster 108 mph ,but you Pootle at 40-50 knots

http://www.google.co.uk/url?sa=t&rc...=1fTkppRr8ga5oeGokmgj_w&bvm=bv.47008514,d.d2k

I thought the OP was looking for a comfortable family boat, what use would that thing be to him.

 

[rbcoomer]

Is there any means of getting high speeds without slamming? I thought that was part of the thrill! You either slow down to a speed better suited to the length of the waves or expect to get a bit bumped about and/or wet occasionally. Speed and smooth ride are somewhat of a paradox on the water - If you want a smooth ride then you need to pick flat seas or get a much bigger boat.

Personally I love being out there no matter what and some of the best days out can leave you black & blue (must be some inner Raggie), but I wouldn't want to batter the family about on a leisure trip and thus would only pick relatively flat water for them. (Although they'd disagree as SWMBO & son are speed freaks more than me )

Wipe-out didn't say they were looking for speed however - just a smoother ride when the sea wakes up a bit.

On that basis I'd agree that you: a) need to get the best out of existing boat - either by gaining as much experience as possible in varying conditions (within reason!) or some own-boat tuition to read/work with conditions as much as possible; or b) you need to get a bigger, semi-displacement or deeper V planing hull.

 

[Portofino]

I thought the OP was looking for a comfortable family boat, what use would that thing be to him.

-
8ugger al use ,I,am not suggesting he goes out and buys one
I,am trying to answer " what single factor" to look for in hull s to minimise slamming .
These are illustrations of the pionts I have put forward
1 deeper the V
2 narrow beam
3 if you read my post power of the engines so you can throttle back to 1/2 speed and still be going some in a big sea
You say this design is " positively dangerous" the Donzi specifically mentions
Easy handling in a " quartering and following sea"
Yet offer up no alternative design Pic, Vids or explanation or what he should be looking out for .
I think SS know a thing or two about hull design in the 25-40 ftr segment they have produced a
A lot of long thin, pointy deep V boats driven by outdrives that can takle head seas at speed and are not " dangerous" In following seas .
Slamming if it takes off ,lifts etc and then re enters softly ie does not bang crash ,wallop, nothing is displaced ,ie locker doors stay closed .
Then that's not slamming in my book.
My boat has a deep V it's planes at 18 knots, I have reached 40 on the GPS
I often slow it down 22 or even 18-19 if v rough by trimming the pointed bow down ,but need power to keep it on the plane
In a following sea ,to prevent it diving in then i simply trim it bow up and slow down .
There is a big difference in bouncing softly amd slamming - you can here it

 

[hlb]

-
8ugger al use ,I,am not suggesting he goes out and buys one
I,am trying to answer " what single factor" to look for in hull s to minimise slamming .
These are illustrations of the pionts I have put forward
1 deeper the V
2 narrow beam
3 if you read my post power of the engines so you can throttle back to 1/2 speed and still be going some in a big sea
You say this design is " positively dangerous" the Donzi specifically mentions
Easy handling in a " quartering and following sea"
Yet offer up no alternative design Pic, Vids or explanation or what he should be looking out for .
I think SS know a thing or two about hull design in the 25-40 ftr segment they have produced a
A lot of long thin, pointy deep V boats driven by outdrives that can takle head seas at speed and are not " dangerous" In following seas .
Slamming if it takes off ,lifts etc and then re enters softly ie does not bang crash ,wallop, nothing is displaced ,ie locker doors stay closed .
Then that's not slamming in my book.
My boat has a deep V it's planes at 18 knots, I have reached 40 on the GPS
I often slow it down 22 or even 18-19 if v rough by trimming the pointed bow down ,but need power to keep it on the plane
In a following sea ,to prevent it diving in then i simply trim it bow up and slow down .
There is a big difference in bouncing softly amd slamming - you can here it

I thort the OP was looking for advice, not wanting to design a new boat. Older SS are mainly dog rough.

I told him where to look for good design and can still be bought from his eighties design and rated at the time by MBY or was it MBM as unbelievable, he revolutionised motor boat design. But only from about 35ft upwards.

To save you the trouble it's here. http://www.olesinski.co.uk/