Hobbyhorsing: something like a flopper stopper?

[Greg K]

Originally Posted by GordMay

Greetings and welcome aboard the CF, SVKemily.

Heavy ends produce a slower, steadier [frequency], but more extreme [amplitude] pitch.
Lighter ends producer a faster, jerkier, but less extreme pitch.
Pick your poison.

This.

I've had two boats that hobbyhorsed, both Alberg full keel designs with significant overhangs. ...similar to your Mason. My choice has always been neither to purposely load the ends nor to lighten them but, rather, to spread out the weight throughout the full length of the boat as evenly as possible. From a practical standpoint, especially for a cruising boat, it makes sense to utilize all storage space in the most practical and convenient manner but, with a little forethought, it can be done so that it also minimizes the fast, jerky pitching by evenly spreading out the weight to increase inertia.

[SVKemily]

Re: Mason 32 vs. 33: this is a one-off built in Ontario, Canada. I haven't measured the LOA myself but, unlike the Mason 33 pictured on sailboatdata.com, my boat does have davits. I should ask the previous owner where he got the design so that I have my story straight.

Displacement: My 3700lbs figure was very approximate. I took the 24' LWL from the listing, multiplied it by the 10' beam, multiplied it by 0.5' depth, then by the density of water and divided by two because the hull is not a rectangle. I should probably have dropped a significant figure and called it "about 3000-4000 lbs".

I'm comparing the motion to sailboats of similar length, facing the same direction, 1-4 slips over. I don't plan on staying in the marina long-term but I'm hoping to cruise most of next summer and am concerned that the motion in the marina may be a preview of the motion at anchor and moorings. And of course I will likely spend some nights in marinas.

Thanks for all the additional ideas! I will try a uniform weight distribution in addition to a centered one, and if I see hobbyhorsing at anchor I'll try putting the dinghy in the water and also the riding sail, chain retention, kellet and drogue ideas.

[Cheechako]

I would caution using the marina as a basis for whether the boat hobby horses, or rolls for that matter. I have watched boats in the marina from above in wind and weather and found certain boats in certain spots would roll heavily, even though they were newer design boats. Was it the boats? or was it the spot? Or water flow? Hard to say..... but pretty enlightening to see a modern boat roll almost to the point of masts hitting the boat on either side, while those outer boats are not rolling much at all.

However the Mason is a bit old school, not severely but somewhat with the medium waterline to OAL. Is there wave action in the marina? Hobbyhorsing is usually a result of wave action combined with short waterline and /or weight in the ends, but most marinas are built to eliminate wind waves in the marina.....

Is it a Mason 32 or 33? I had not heard of a 32.....

[TrentePieds]

Kemily said: "Displacement: My 3700lbs figure was very approximate. I took the 24' LWL from the listing, multiplied it by the 10' beam, multiplied it by 0.5' depth, then by the density of water and divided by two because the hull is not a rectangle."

You are absolutely on the right track, but using half a foot for one of your parameters doesn't wash. And divided by 2 :-)??? I take it you were guestimating the so-called water plane coefficient ("Cwp")? It is the quotient you get when you divide the ACTUAL area of the plane at the design water line with the area of a rectangle that circumscribes the the water line plane.

I don't know what Cwp ACTUALLY is for your boat, but it won't be .50. .60 would be in the ballpark for a boat like the Mason33. The circumscribed rectangle is, as you said, 25 x 10 = 250 SqFt. Apply the Cwp [MY Cwp :-)], and you an area for the waterline plane of 250 x .60 = 150 SqFt,

In yacht design we talk of “pounds per inch immersion”. Not “per FOOT immersion” That's big ship stuff. PPII is [amazingly :-)] the number of pounds it will take to settle the hull one single inch. Now, therefore, if you settle the Mason32 one single inch, you will have made her submerged volume greater by 150/12 CuFt, i.e. by 12.5 CuFt. Since the briney is taken to weigh 64lbs per CuFt, 12.5 CuFt of briney will weigh 806.25lbs and that is therefore the weight you will have to take aboard to settle her a single inch.

Given the overhangs on the Mason32 each SUCCESSIVE inch of immersion will carry a bit more, but let's ignore that detail. To settle your boat 5” (which is where we started) will take 5 x 806.25 = 4,031.25 pounds plus a bit for the kiddies. Call it 4,200 lbs.

The Cwp is also called the “fineness ratio” and your “pounds per inch” will vary greatly depending on what your boat's Cwp ACTUALLY is. Play with the numbers and see.

In TrentePieds, which has the same 25Ft LWL and a WLB (“breadth” or beam on the design waterline) of 8'6", I reckon that MyBeloved, the kitty-kat and I, with enough provisions and general clobber for a 6 weeks coastal cruise, load her with about half a ton, call it 1,200lbs. So she'll settle an inch and a half or two inches which makes no odds to her handling.

Others have already dealt with the hobby-horsing. You can have pitchy or you can have wet. But in any kind of “weather” it's always both wet and pitchy, so why worry about it ;-)? You will find that having a wave periodicity that really sets the boat to “hobby-horsing” is something that only happens on frosty Fridays. When it does, take some Gravol ;-)!

All the best

TrentePieds

[wingssail]

Originally Posted by SVKemily

Hi everyone,

I have noticed that my new (to me) Mason 32 hobbyhorses (or pitches, or rocks fore-and-aft) quite a bit more than neighboring boats in the marina. I understand that the spoon bow shape can be especially prone to hobbyhorsing.

The previous owner has told me that when loaded for cruising it sits about 5" lower in the water, which means it would have displaced approximately 3700lbs more. From what I have read, concentrating that extra ballast near the beam could reduce hobbyhorsing.

I'm wondering whether it's possible to supplement the effect of that ballast with something like a flopper stopper, deployed off the bow or stern. I haven't found any accounts of anyone trying this, or any recommendations for or against.

Has anyone tried it, or does anyone have any non-ballast hobbyhorsing countermeasures to share?

Thanks in advance!

There is possibly some subjectivity going on here, perhaps your boat is not moving that much differently than others, it might just look that way to you.

But there are some factors which impact how a boat moves in waves:

How much buoyancy in the bow? A boat with fine ends, particularly a fine bow, won't rise as much when a wave tries to lift the bow. A boat with a full bow has more buoyancy, and will lift more. Your boat is quite full in the bow.

Long overhangs: A boat with a long overhanging bow and a short waterline may move differently when a wave comes to the bow.

Weight in the ends. Inertia of weight far from the center of the boat exacerbates hobby horsing (sorry, I know you didn't want ballast related issues.) People who load up boats with stores in the ends, and structures (such as arches), anchors, etc in the ends will have more hobbyhorseing.

Mast length and keel length: Tall masts and deep keels add resistance to hobby horsing.

These might be considered characteristics of cruising boats with full bows, short masts and keels, and weight in the ends. If so, it will be worse if you motor or sail into waves, which is one of the reasons why some cruisers complain about "terrible” passages into choppy waves: it goes with the boat type.

[Thumbs Up]

Originally Posted by SVKemily

Re: Mason 32 vs. 33: this is a one-off built in Ontario, Canada. I haven't measured the LOA myself but, unlike the Mason 33 pictured on sailboatdata.com, my boat does have davits. I should ask the previous owner where he got the design so that I have my story straight.

Displacement: My 3700lbs figure was very approximate. I took the 24' LWL from the listing, multiplied it by the 10' beam, multiplied it by 0.5' depth, then by the density of water and divided by two because the hull is not a rectangle. I should probably have dropped a significant figure and called it "about 3000-4000 lbs".

I'm comparing the motion to sailboats of similar length, facing the same direction, 1-4 slips over. I don't plan on staying in the marina long-term but I'm hoping to cruise most of next summer and am concerned that the motion in the marina may be a preview of the motion at anchor and moorings. And of course I will likely spend some nights in marinas.

Thanks for all the additional ideas! I will try a uniform weight distribution in addition to a centered one, and if I see hobbyhorsing at anchor I'll try putting the dinghy in the water and also the riding sail, chain retention, kellet and drogue ideas.

The fact that it is a one off is a good clue. I had a one off mahogany strip sloop once. It had lead ingots in the bilge. I was told never to remove them, the ballast was added because the boat was tender. You could be under ballasted.

[MicHughV]

I can't say I've ever known a sailboat to hobby horse while tied up to slip.???

Is the correct terminology being used here ???

"hobby horse" is taken to mean a similarity to a rocking horse moving back and forth with a child on it.
applied to a sailboat it means the boat is rocking around it's midsection, ie, the bow and stern are pitching up and down.

Tied up in it's slip, I don't see how this could happen, unless off course, the slip is experience significant wave action, which would cause most any boat to pitch up and down.

With the boat 5" below it's lines, it means more hull is in the water....ie, more girth, which would tend to lessen hobby horsing as there would be more displacement to trying to push down in the water.

Some years ago, I was tied up at a transient slip, that was open to wave action which caused my boat to rock up and down whenever another boat passed by, but I think most any boat would behave in a similar manner.

[Thumbs Up]

The other term is pitching, same thing. The waterline could be subjective, especially on a one off. A lot of speculation. SVKemily, can you post photos by chance? Any out of the water photos? Also if the other boats around you have different hull shapes or are different types of boats it is not comparing apples to apples. Also not sure what you mean about a spoon bow. What I think of as a being spoon bow would reduce pitching (more bouyant forward) whereas a fine entry would be more amenable to pitching.

[JPA Cate]

Fine entry, little flair, and a narrow stern do tend towards hobbyhorsing. If you have a wide stern, though, a fine entry doesn't encourage pitching, because the broad stern stops it from going down.

I think the suggestion for a riding sail would help in this instance, and I would be concerned with chafing issues deploying a flopper stopper forward. I would also suggest sleeping midships if the motion bothers you at anchor. put the settee cushion on the cabin sole, and use a sleeping bag to keep warm, if necessary. Least motion is amidships. The good news is that to some extent, your body will accommodate to the motion, over time, especially if you have a positive attitude about it doing so.

Ann

[SVKemily]

Sure. Here it is in its slip on a calm day: https://photos.app.goo.gl/DBQtrxgyjEkupjUn7

The slip does get quite a bit of wave action when there is wind. Sorry about the sail covers, I am doing a better job with those by this point.

Here it is out of the water: https://photos.app.goo.gl/M499WhZ2HEqdAGQA7

Here is a photo from the PO, showing it sitting quite a bit lower in the water than it is now: https://photos.app.goo.gl/pCheTxdTTnkGUica7

It's certainly possible that the hobbyhorsing is subjective. I stared at it and the neighboring boats for quite a while last visit. I will take a video next visit if there's wave action in the marina.

I hadn't considered the tradeoff between hobbyhorsing and a wet ride, but it does make sense that less of one would lead to more of the other. Thanks for the silver lining! And for the tutorial on pounds per inch of immersion.

Also, I have learned that Kemily was not quite a one-off. Karmac Yachts of Hamilton, ON produced four of these boats. However, the sister boats were sloops without a pilothouse. Here's one of them: https://photos.app.goo.gl/VpXSKbZd9HFpTFb98 Everything I know about Karmac I just learned from the listing for this other boat, which does not look like a sister boat: https://www.sailboatlistings.com/view/90879

[Thumbs Up]

She is pretty! Hope you don't mind me linking an old listing. It shows the stern as well. https://www.boatdealers.ca/boats-for...oronto-ontario

[Thumbs Up]

It looks like the hull shape may be a contributing factor. (kind of has a rocking chair curve to the hull. I think with some more weight (cruising gear and provisions) she will settle down. She probably sails fine and won't pitch once heeled slightly but going downwind in steep chop is bound to get bouncy. All boats are built to a set of compromises. I guarantee that you will pitch way less than a Hitchhiker catamaran.

[Stu Jackson]

Originally Posted by SVKemily

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In the likely event that my actual cruising gear doesn't weigh that much, I can supplement it with some well-secured internal ballast, for now.

Welcome, nice boat, had a neighbor for many years with one. Remember him fondly because when I helped him move his old batteries out, the acid ruined a good pair of shorts! IIRC, his batteries were far aft under the aft bunk.


That said, do NOT add "internal ballast" UNLESS it is batteries, and centered in the right place. The best weight you can add is useful weight.

[Thumbs Up]

And YES to the flopper stopper if you want more comfort at the dock, but when you are not there let her rock away, it won't hurt a thing. Just make sure you use some spring lines and leave enough slack in the bow and stern lines.

[TrentePieds]

One more thing, Kemily, if I may:

She's a pretty thing, and with the pilot house, she'll serve you well in all weathers - Even Twanna's :-)!

It's unlikely you'll ever find the lines drawings for her, so we have no real way of determining the sundry ratios and coefficients that are hers. But you can be sure they are okay. Al Mason ALWAYS got it right :-)!

What would be a very useful thing to do, is, next time you haul 'er, to get all the clobber out of her before you haul. Then have the yard weigh her in the slings. That'll give you her LIGHT displacement and a lot of things can be "worked backwards" from that.

You might like to know the TrentePieds is also a pilot house sloop.

And now I invite you to consider "hobby-horsing" in light of two "limiting cases". Remember the designs of a hundred-odd years ago that were referred to as "plank on edge"? Consider a REAL plank, ballasted on one side to it really does float "on edge". And then an identical plank without the ballast so it floats on its side. Which of the two will drive through the waves without pitching very much at all, and which will be thrown about horrendously? So there you have it :-) A quickie tutorial on "hobby-horsing".

So unlax. You've nothing to worry about. Al M knew his stuff! But do get 'er weighed :-)

All the best!

TP