Weight in the ends of a Boat

I think boat design is relevant here. A fat sterned yacht will carry plenty of weight in the stern with minimal impact on performance. Apply the same weight to the relatively fine bow and you will see a big difference in motion.
A couple of years a go we were carrying all the materials for a teak deck replacement project in the forepeak as we had no where else to put it. The saloon floor had new teak piled high. We had an 80 mile beat to windward from St Martin to Antigua. The motion of the boat with all the weight forward was terrible. The speed dropped a couple of knots. We moved as much of the weight to the saloon and the motion improved dramatically. We now try to carry as much weight in the middle of the boat as possible and save the light stuff like empty fuel and water cans in the bow locker. We keep the heavy diving bottles and spare anchors in the stern locker as the weight has less impact on motion here.
The boat in question is not a lightweight flyer. With normal live aboard gear we weigh in at circa 19 tons so even with a heavy boat the distribution of weight matters.
 
geem said:
I think boat design is relevant here. A fat sterned yacht will carry plenty of weight in the stern with minimal impact on performance. Apply the same weight to the relatively fine bow and you will see a big difference in motion.
A couple of years a go we were carrying all the materials for a teak deck replacement project in the forepeak as we had no where else to put it. The saloon floor had new teak piled high. We had an 80 mile beat to windward from St Martin to Antigua. The motion of the boat with all the weight forward was terrible. The speed dropped a couple of knots. We moved as much of the weight to the saloon and the motion improved dramatically. We now try to carry as much weight in the middle of the boat as possible and save the light stuff like empty fuel and water cans in the bow locker. We keep the heavy diving bottles and spare anchors in the stern locker as the weight has less impact on motion here.
The boat in question is not a lightweight flyer. With normal live aboard gear we weigh in at circa 19 tons so even with a heavy boat the distribution of weight matters.
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But with all that weight in the bows I assume that she was pitched forward, bows down, moving CofE well forward of CLR, disrupting the balance, requiring lots of additional effort on the helm to keep her tracking straight.

What would have been interesting would be if you had had the weight fore and aft and then piled it all in the cabin without affecting trim.
 
From my experience, but I can be wrong because I absolutely hate slamming and try to find a way to avoid it (when I really have to drive against waves), more weight at the bow reduces slamming.
 
jac said:
But with all that weight in the bows I assume that she was pitched forward, bows down, moving CofE well forward of CLR, disrupting the balance, requiring lots of additional effort on the helm to keep her tracking straight.

What would have been interesting would be if you had had the weight fore and aft and then piled it all in the cabin without affecting trim.
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The boat can carry huge amounts of gear and she takes weight extremely well. We didnt notice any dramatic bows down attitude before we left. The steering wasnt effected she just slammed through the waves rather than lifted to them.
 
TQA said:
...weight in the ends might matter if you have a small lightweight, used for racing, where 2 seconds a mile is a big deal...
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I never race, but maybe I could carry my little Danforth at the bow, and gain quarter of a knot through a longer waterline? ;)

Screenshot_2017-01-14-18-03-14_zpswahxuqc1.png
 
dancrane said:
I never race, but maybe I could carry my little Danforth at the bow, and gain quarter of a knot through a longer waterline? ;)

Screenshot_2017-01-14-18-03-14_zpswahxuqc1.png
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If it's light air, you could move your backside forward a bit and keep the transom nicely clear of the water.
Osprey hull slips through the water with much less wake than shorter things in those conditions.
In my boat in light air, I end up forwards of the thwart, even with a crew.
 
I'm sure that's good advice, thanks LW. My mate who took the pic from his Contender, habitually sits too far aft and sags pitiably behind the slowest designs in the handicap fleet...

...I tell him his transom is partly under water, which can't improve his speed, but it never occurred to me that mine might be, too. :rolleyes:
 
As already noted, higher weight in the ends of the boat add pitch and yaw inertia. This means the natural pitch frequency (pendulum effect was the neat phrase used) becomes longer.

Going to windward, if the frequency of the waves hitting the boat matches this natural boat frequency, the boat will "hobby horse". or exaggerate its pitching movement.

If your boat "hobby horses" frequently in your local conditions (wind, fetch etc) it'll slow down. So it then may be useful to add/subtract more weight in bow and stern to "de-tune" the boat's natural pitching movement from the wave frequency.
 
Good advice again, thanks Mike. I guess helming a two/three man boat alone, messes with the intended trim of the hull.
 
There are other factors involved with moving weight forward, as in a dinghy. Some time in the last century when I sailed Fireflies we usually sat near the shrouds when singlehanding to windward. My impression at the time, and I wasn't a very scientific racer, was that the main gain was an improvement in trim, with an increase in weather helm, so that the boat "wanted" to sail into the wind. In my 34' cruiser I don't see much difference with weight alterations. I have a 45lb CQR in the now roller, 40m of chain, and up to 250l of water in the fore-peak. We got rid of most of this when we did a regatta, but in mostly light winds didn't see much difference.
 
johnalison said:
...the main gain was an improvement in trim, with an increase in weather helm, so that the boat "wanted" to sail into the wind.
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That's interesting. If sitting forward caused the mast to be more upright, or less inclined to be raked back than with the crew well aft, one might expect the centre of effort to be drawn forward, making the boat less, rather than more inclined to point into the wind.

My forefoot stands above the water by Mr Proctor's design, I think...although I've never seen an Osprey with three men aboard.

Screenshot_2017-01-15-17-58-13_zpsza7legly.png


My earlier remark about the Danforth wasn't entirely a joke. Fitting the asymmetric may require a short sprit, from which the anchor could hang after hauling up, without bashing the gelcoat. Its small weight so far forward might help my trim and hull-speed.
 
I suspect the top Osprey sailors might be raking the mast back upwind?
I was watching some Merlins a while back. As they rounded the leeward mark, the crews move forward, getting the transom out and the bow in. Then the top of the mast moved back about 2ft as they pulled on the rake controls.
 
Again, interesting; I wish I knew. I think raking the Osp rig is reserved for heavy weather, but thinking back, I really wouldn't know...

...one day this year a kind old honorary member of my club tapped his pipe out on the steps from which he'd watched me hosing the salt off my decks, and observed, "you know, the top of your mast is about a foot further forward than the bottom". I hadn't noticed, by sight or feel at the helm, but I was glad of the hint! :rolleyes:
 
With a dinghy crew weight forward, you would expect the centre of effort to me forward, and with the centreboard tilted aft, the centre of LR to move aft, but I imagine that getting the bow to bite into the water changes this. It may also be that the asymmetric shape when the boat is slightly heeled will also have a dynamic effect.
 
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