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Old 04-29-2015
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guar guar is offline
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Default Boats that should go on a diet

It's believed that most of the Dash 34s are overweight. Anyone have an idea of just how much?

I've seen several published displacements for them. The most common number seems to be 5900 lbs although i have seen 5300, which seems a bit unrealistic. I sailed on Balderdash many years go and I can't remember how much the owner said it weighed, but I do recall him saying it was 1200 lb overweight, so I'm guessing she tipped the scales at over 7000 lb.

So where would the additional 1200 lb come from?

I doubt it would be the keel since no one is going to incur the cost of 1200 lb lead.

The designer would provide the builder with the lam schedule. so assuming they follow the lam schedule, that would mean almost 1200 lb of additional resin. I doubt the sloppiest wettest layup could do that, in fact I think it almost impossible. A few hundred pounds I can see but not 1200.

Unless the builder decided to take it upon themselves to increase the lam schedule, which again doesn't make sense due to the increased cost

So is it more likely that they are not overweight by that much and it was simply a weighing error in the case of Balderdash? I know Manana has said the sling angle (if it's not 90 degrees) can make a difference and I agree with that.
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Old 04-29-2015
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Schnick Schnick is offline
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Most production boats are overweight by at least a few hundred pounds from the designer specs.

J boats, just for example, is notorious for this, with measured weights in the J/35 and J/120 classes ranging over many hundreds of pounds.

Catalina has a policy of publishing displacement numbers that do not include motors or interior fixtures, so their boats almost always ARE a thousand pounds heavier than the brochure states. For my 36, I figured it weighed about a thousand over the brochure numbers, BUT also probably 2000 less than a lot of the other 36es out there that had full cruising gear in place. For that particular model the brochure displacement increased 3000 pounds with no change to the boat spec, about 3 years after production started. (from 12500 to 15500)

Since PHRF ratings are based on observed performance, what I believe is really important is being the same weight as the other sisterships you are racing against.

For a typical 34 footer, a thousand pounds will sink the boat an inch or more from it's normal lines, so the truly overweight boats should be easy to pick out.

When you see someone say, oh yeah, this boat is slow because it has 2000 pounds of extra furniture compared to so and so's boat, and then the bow knuckles are floating in the same orientation, fell free to slap them upside the head.

No weight reported by a travelift is of ANY use in judging the true weight of a boat within more than 3000 pounds.
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Old 04-29-2015
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My c&c 110 was weighed in a tank @ 13,500 lbs - that is 2600 lbs over designed published weight........ and I am sure it was that heavy! In speaking to other 110 owners around the country they had similar results........

My take on it is that the builder designer wanted the boat to weigh in @ 10,900 for selling reasons but just couldn't deliver.
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Old 04-29-2015
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Schnick Schnick is offline
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Another thing that I am sure you are aware of, the final few Dashes were built without the interior moulding / headliner overhead. That's probably good for a few pounds, and tough to say whether it was called for initially or not?

Guar you are in the fortunate position of doing a 'frame off' rebuild, just don't put anything on the boat that doesn't need to be there, and you should come out just fine?
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Old 04-29-2015
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I guess the intent of my original post is to point out that it is pretty tough for a boat to come out significantly overweight unless the published number is based on the marketing departments numbers or you are relying on flawed weighing methods.

I suspect most builders would look for ways of reducing rather than adding weight mainly because lbs = $

I'm slowly removing the liner, more for structural rather than weight issues since I plan to relocate the main bulkhead. From a few spot measurements of the liner thickness, I figure the liner adds about 100 lb although whatever I replace it with will probably add close to that amount back. Right now I'm thinking about applying fairing compound which I think is what is used on the Davo, or at least that is what it looked like after several beer on a cold and wet winter evening.

Removing the liner is slow because it is bonded to the inner skin with mat on the cabin sides. Cabin top should be comparatively easy since it seems to be spot bonded. Ideally, I would just remove the cabin top portion of the liner, but I had to cut up into the cabin side a few inches to get the new inner skin to overlap onto the old one and to insert some new balsa into the cabin side in a small area. You can see this in the attached photos of the balsa core replacement. Not my finest work but tricky to lay up the glass upside down.
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Old 04-29-2015
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Manana Manana is offline
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Published displacements are hopeful "guestimates" at best...

The only true displacement measurement can be taken from a load cel when the boat is lifted by a single point. Great for Martin 242's, J 24's and the like, but problematic for most 30+ foot racer cruisers...

Could weight have been saved from the Dash 34? Of course, the original builder (Spencer Yachts) used woven roving and mat for the inner and outer skins. Roving is notorious for absorbing copious amounts of resin. I'm pretty sure a modern laminate schedule utilizing nothing exotic would see a moderate reduction in displacement. Go all out and use exotic fibres and cores with a vacuum bag/pre-preg system and you could realize even greater weight savings.

But at what cost?
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Old 04-29-2015
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henryr henryr is offline
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For measurement based rules (ORR, IRC and ORC (AFAIK)), displacement is determined by measuring freeboards at specified locations, along with the water density. Then if you have the vessel hydrostatics, easy peasy to get displacement.

I think it would be interesting to check the freeboards on the local Expresses, just to satisfy couriosity. I'd bet Mannana and Avalanche are pretty close, but the green one at Royal Van is probably a good bit heavier with all the cruising kit they have.

Agree with Trevor, that many production hulls are overweight due to excess resin, but then they also drastically underestimate the weight of the outfitting too.
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Old 04-29-2015
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Quote:
Originally Posted by Manana View Post
Of course, the original builder (Spencer Yachts) used woven roving and mat for the inner and outer skins. Roving is notorious for absorbing copious amounts of resin. I'm pretty sure a modern laminate schedule utilizing nothing exotic would see a moderate reduction in displacement. Go all out and use exotic fibres and cores with a vacuum bag/pre-preg system and you could realize even greater weight savings.
But I suspect LD specified woven roving in the original lam schedule because - what else was there at the time, or at least what would any other production builder have used? So while it could be built lighter today, it was probably pretty much state of the art for a production boat. I think the old literature on the boat says UD fiberglass was used in the construction.

Another thing I am curious about is the hull core. General consensus is it is balsa cored and I haven't done any exploratory work on the hull, but one piece of literature (see attached) says it is foam cored - the hull anyway. Mind you, the same literature also appears to indicate a displacement of 5300 lbs. Can anyone confirm it is balsa? I have no issues with balsa just curious.
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Old 04-29-2015
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Quote:
Originally Posted by henryr View Post
Agree with Trevor, that many production hulls are overweight due to excess resin, but then they also drastically underestimate the weight of the outfitting too.
But is it really excess resin? I would think the designer would take into account the attainable resin/glass ratios based on the type of glass specified in the lam schedule and the layup method. In other words, these factors would or should be accounted for in the weight study - which should also account for outfitting as well. Or are weight studies not done in smaller production boats? I don't know, but I would have thought so.

I do know it's not easy to get excess resin considerably beyond the saturation point of the glass without the resin either running off or pooling - unless a thickener is used.
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Old 04-29-2015
ShawMac ShawMac is offline
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I hauled out with a 40 ton crane this time and I think they measure weight pretty carefully (as the operator's safety depends on it when considering reach). I had removed most everything that wasn't bolted down and she tipped the scales at 7900 lbs after the rig was pulled. Design displacement is 6700-7000 depending on the literature you read. I had told the operator 8000 as an estimate thinking I had some safety cushion there. Apparently not very much!

I'll be interested to see what she weighs going back in after sitting in a dry shop for 3 months.
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