Hobby horsing vs slam

[cmedsailor]

Is there any difference between the two?
My understanding is that hobbyhorsing is the tendency of a boat to pitch back and forth. Slamming, I guess it's the same, though when my boat slams for example it's really the bow that moves a lot (the feeling at least).

 

[jrudge]

No idea re hobby horsing but slamming.

This is when the bow falls hard and basically hits the water as opposed to "slicing" through it.

The boat will jarr noticably and you will be aware you are putting stresses on it that you feel it won't like, and neither will the crew.

It is normally when you are going to fast over rough water. I had a Cranchi that slammed terribly on anything other than flat water. Just slow down or trim the bow down and it can be managed.

 

[webcraft]

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Hobby-horsing refers to a rapid fore and aft rocking motion. Catamarans are the worst culprits apparently, although I didn't experience it on my only Catamaran jaunt.

Slamming is when the bow lifts up high on a wave then drops onto the next one with a bang. It is worse with hulls with flat bow sections.



- W

 

[cmedsailor]

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This is when the bow falls hard and basically hits the water as opposed to "slicing" through it.

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Living in the Med and having to deal with the nasty short chop, unfortunately, I know very well what slamming is!! Probably I should have asked "is hobby horsing the same as slamming?" (probably just different terminology on the other part of the planet).

 

[skipmac]

Living in the Med and having to deal with the nasty short chop, unfortunately, I know very well what slamming is!! Probably I should have asked "is hobby horsing the same as slamming?" (probably just different terminology on the other part of the planet).

My interpretation, hobby horsing is excessive pitching of the boat IE bow and stern going up and down like a seesaw. This may or may not involve slamming when the bow comes down. A boat with V shape sections forward or a fine bow may come down more softly or slice into to water without the slam.

Hobby horsing can be caused by a number of factors.

- Too much weight in the ends of the boat like anchor and lots of chain forward with dink, outboard and more aft.
- Design of the hull perhaps forward sections very full
- Steep choppy waves. Can set up a harmonic with the boats natural motion to exacerbate the problem

 

[RupertW]

I think slamming stops hobby horsing, at least temporarily.

I've had a couple of boats which hobby horsed when beating. When it did result in a slam that stopped the seesaw momentum, uncomfortably. Usually taking over the helm manually helped with both.

 

[prv]

Probably I should have asked "is hobby horsing the same as slamming?"

No, it's not.

Kindred Spirit had a very traditional, pilot-cutter-esque long-keeled shape - the bottom of the hull was a sharp V right from the stemhead to the rudder-post, so she always sliced down into the water and never slammed.

However, the previous owner had fitted a bigger engine which put too much weight aft, and before sailing her (and without realising this) we moved the fuel tank aft as well. The previous owner had counteracted the engine with a block of lead in the bow locker and a very generous set of ground tackle, and once we realised she was stern heavy we tended to stow all loose gear in the forepeak as well. So she suffered seriously from weight in the ends, and in a Solent chop she would sometimes hobby-horse badly. We'd end up pitching back and forth while making no real forward progress - the only solution was to change course across the waves, which may have meant a change of destination. Yet on other days where the wave frequency was different, she would go to windward quite acceptably by the standards of a 24' gaffer.

Pete

 

[michael_w]

When heeled, V shaped hulls present a fairly large flat expanse to the water and as a result can slam quite badly. U shaped sections are not as badly affected. That's according to an article written by Olin Stephens, who ought to know!

 

[macd]

When heeled, V shaped hulls present a fairly large flat expanse to the water and as a result can slam quite badly. U shaped sections are not as badly affected. That's according to an article written by Olin Stephens, who ought to know!

That's certainly logical and matches my experience. My old Rival 32, with its old-fashioned hull form, wasn't regarded as a slammer but occasionally knocked your teeth loose when it barged into the wrong wave when heeled, which of course was when it would present a flat face to the water.

And re prv's post, +1: hobby-horsing and slamming are manifestly not the same thing, although they may sometimes be related. One's a motion, the other's a motion ending with a very loud crash. The worst hobby-horsing I've seen is in heavy, traditional boats with long overhangs (and who-knows-what stored in the them) motoring into a sea.

 

[Cruiser2B]

That's certainly logical and matches my experience. My old Rival 32, with its old-fashioned hull form, wasn't regarded as a slammer but occasionally knocked your teeth loose when it barged into the wrong wave when heeled, which of course was when it would present a flat face to the water.

And re prv's post, +1: hobby-horsing and slamming are manifestly not the same thing, although they may sometimes be related. One's a motion, the other's a motion ending with a very loud crash. The worst hobby-horsing I've seen is in heavy, traditional boats with long overhangs (and who-knows-what stored in the them) motoring into a sea.

Agree it has a lot to do with hull shape, or specifically the shape that meets the next wave. I think it also depends on the wavelength. On longer swells, the boat pitches over the crest, goes down the backside, pitches up in the trough and repeats - reads as hobby-horsing. If the wavelength is short, as the boat pitches forward over the crest it slams into the face of the next wave - result is slamming.

 

[Birdseye]

Is there any difference between the two?
My understanding is that hobbyhorsing is the tendency of a boat to pitch back and forth. Slamming, I guess it's the same, though when my boat slams for example it's really the bow that moves a lot (the feeling at least).

No it isnt the same thing. Hobby horsing is the sort of rocking horse motion that you get in boats that have canoe shaped hulls or something approaching that - like say a HT catamaran. Slamming is what happens when you have flattish inderwater surfaces that hit the sea like a flat hand slapping the water. Slamming is what you tend to get in modern AWBs like bendytoys. Hobbyhorsing is for older designs since the broad sterns of modern boats tends to prevent it.

 

[prv]

On longer swells, the boat pitches over the crest, goes down the backside, pitches up in the trough and repeats - reads as hobby-horsing.

That doesn't sound like hobby-horsing to me, just normal motion in a swell. When Kindred Spirit hobby-horsed, she'd pitch back and forth but the centre of motion (about level with the cabin aft bulkhead on that boat) barely moved at all - like the pivot point on a see-saw. I've also seen it described as "going up and down in the same hole" - it's a powerful feeling of going nowhere while the bowsprit alternately points at the sky and then digs into the sea.

If the wavelength is short, as the boat pitches forward over the crest it slams into the face of the next wave - result is slamming.

Slamming is anything that, well, slams - with a loud bang. But yes, more likely in shorter waves than long rolling ones.

Pete

 

[steve350]

Hobby horsing occurs when pinching too high. Getting some drive in the sails by bearing away is the cure.

 

[cmedsailor]

Interesting answers. For the old fashion (long keel and heavy) it's hobby horsing and for the modern fashion (light fat bottom) is slamming. I am wondering what's worst?
PS: I HATE it when my boat slams by the way....

 

[steve350]

J.D. Sleightholme: "In a tumble of waves and a moderate to fresh breeze, it is far better to slip easily past the seas rather than try to smash through them. A good full-and-by course is the fastest in the end. To stick a small cruiser tight to the wind, and expect her to generate power enough to bulldoze her way through, is to induce that tiresome hobby-horse motion which gets you nowhere."

 

[charles_reed]

Living in the Med and having to deal with the nasty short chop, unfortunately, I know very well what slamming is!! Probably I should have asked "is hobby horsing the same as slamming?" (probably just different terminology on the other part of the planet).

No, hobby horsing means you go 2 steps forward and 1 back - slamming is when you fall out of one wave and hit the hole in the centre - your teeth meet through your tongue and you hear the crash of broken crockery (even Melamine) from down below.
Both occur in the Med - hobby horsing at anchor.

 

[prv]

J.D. Sleightholme: "In a tumble of waves and a moderate to fresh breeze, it is far better to slip easily past the seas rather than try to smash through them. A good full-and-by course is the fastest in the end. To stick a small cruiser tight to the wind, and expect her to generate power enough to bulldoze her way through, is to induce that tiresome hobby-horse motion which gets you nowhere."

+1

The latter is definitely what I was doing with Kindred Spirit in the early days. I learned eventually.

Pete

 

[cmedsailor]

slamming is when you fall out of one wave and hit the hole in the centre - your teeth meet through your tongue and you hear the crash of broken crockery (even Melamine) from down below.
Both occur in the Med - hobby horsing at anchor.

Two o clock after mid night, veeery dark (no moon), August 2013, sailing below Attalia bay going towards the west in a nasty swell coming from both west and north. I reduced the speed to only around 3 knots (for some endless hours) due to the confused sea when suddenly....there was no water below my keel! A very very bad slam/drop, speed went to zero, the mast shaked a lot and the whole boat rocked. I think it was the scariest moment of my life so far.

 

[charles_reed]

+1

The latter is definitely what I was doing with Kindred Spirit in the early days. I learned eventually.

Pete

Lovely in theory, impossible in practice in the Med - because the wind dies away and the seas keep on coming...
It's especially bad in a lightweight boat - a full-keel heavyweight comes into its own in that situation.

 

[Nico]

Hobby horsing can be caused by a number of factors.

- Too much weight in the ends of the boat like anchor and lots of chain forward with dink, outboard and more aft.
- Design of the hull perhaps forward sections very full

I'd have thought narrow fore and aft sections would increase hobby-horsing as they offer little buoyancy. A fuller midships would then act as a pivot.