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Hanse 418 - Glued in Keel grid repair (vid)


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So we've all seen videos of inexperienced couples trying to repair the structural floor pans that are all the rage in cheaper production builders today. 
Well I actually just stumbled across this video of a professional repair being done at a yard in Stockholm. 

I've not finished it yet so don't know how good the finished product will be, but thought it might interest a few a people to see one of these done as a 'pro' job. (it looks expensive) 

Looks like its been heavily grounded as the keel can literally be pushed up into the hull at the aft end.

 

 

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(it looks expensive) 

I think it generally totals boats because of the cost of repairing it.

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16 minutes ago, SloopJonB said:

I think it generally totals boats because of the cost of repairing it.

It's the dark side of the glossy boat shows of the 20th century: most of the craft on display are built in a way which leads to the boat being a possible write-off after a relatively modest impact.

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42 minutes ago, SloopJonB said:

(it looks expensive) 

I think it generally totals boats because of the cost of repairing it.

Typical British understatement from me. 

Interesting that the yard chose to go with polyester for this repair, presumably partly from a cost side, and they laid the glass over a polyester adhesive, presumably for better mechanical bonding. Interested to see if the glass guys on here have a take on that. 

Also I wasn't aware before this video, just how poorly those liners are bonded in situ. 

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1 hour ago, MiddayGun said:

Also I wasn't aware before this video, just how poorly those liners are bonded in situ. 

Whaddya want for 1/2 $million?

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Can't say I agree with cutting up the grid. He might not know how it is built - and how he should taper out repair and rebuild it. I know in the Beneteaus they use unidirectional e-glass on the top flange of the grid. You cut that, you really need to replace it with uni, not just some biaxial or double bias.

Even though it costs more epoxy is just so much better for structural repairs. Compared to the cost of the boat, what's a thousand dollars extra for epoxy?

Be curious how many gallons of resin Expedition Evans used for their repairs. 

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18 minutes ago, Zonker said:

Can't say I agree with cutting up the grid. He might not know how it is built - and how he should taper out repair and rebuild it. I know in the Beneteaus they use unidirectional e-glass on the top flange of the grid. You cut that, you really need to replace it with uni, not just some biaxial or double bias.

I guess that the difference between a good repairer and a cowboy is that the good one gets all that structural data from the designer/builder, then has a structural engineer draw up the repair plan to exceed the strength of the original inadequate structure.

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19 minutes ago, TwoLegged said:

I guess that the difference between a good repairer and a cowboy is that the good one gets all that structural data from the designer/builder, then has a structural engineer draw up the repair plan to exceed the strength of the original inadequate structure.

Yes but we all know Beneteau wont supply that data so a grounded Bene is a write off as its now un-insurable.
Been some threads on that....

 

Didnt see the part where the hull was ultra sonic tested so is there de-lamination in the hull that you cant see?

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1 minute ago, Sailabout said:

Yes but we all know Beneteau wont supply that data so a grounded Bene is a write off as its now un-insurable.
Been some threads on that....

Ah, I missed that.  What a scummy practice.  It makes buying a Beneteau (new or used) into a massive risk.

Is Hanse any more forthcoming?

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I didn't know that. Beneteau could have them sign a NDA if you really cared. 

To determine a laminate, in order of accuracy:

1)  If you can't get the information, just take an angle grinder with a 50 grit disc. SLOWLY take off the gelcoat. Note the type of glass in the top layer (probably 1-2 layers double bias). Slowly grind down each layer and note what is there. If you have an educated eye you can probably eyeball the weight of fabric. If it is like Beneteau it will be probably 2 layers x 450 double bias, several layers of 300-600 gram uni, and 2 or so more layers of double bias (the top flange). Bigger boats will have a few layers of double bias in the middle of the stack. Measure the total thickness too and compare that to publicly available data on laminate thickness.  Vectorply lists all their fabric thickness for open mold and vacuum bagged process.

Option 2)  Take that chunk the guy carved out. Separate the top flange from the side web. Burn the resin with a MAPP propane torch until it's all gone. Then carefully separate the layers, noting the orientation. You'll need an accurate digital scale accurate to 0.1 gram to determine the fabric weight. (disclaimer; I haven't done this but I think if done carefully you won't blow the fibers around and lose them. 

Option 3)  take it to a lab that does "Burnout tests". https://proboat.com/wp-content/uploads/2011/04/burnouttest125low.pdf 

For the amount you are in investing in a repair a few hundred $ in lab tests might be worth it.
 

You're not going to get a structural engineer to design a new laminate. Just recreate what was there, and maybe increase it a bit, depending on your skill level/if you are going to vacuum bag it because the originals might have been vacuum bagged. Maybe. If you just cut off the bottom of the grid tabs, and re-tape, I'd just skip bagging the new tabbing. Use generous scarf ratios; 20:1 or more and then you won't have to worry about them either.

 

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One of the members on the Ericson site recently shared a similar story with his E32, in a series of blog posts.  His yard also opted to cut through the grid, though AFAIK, the reasons for the decision were not explained.  Or I missed that nuance.  

http://sailboatrefit.com/a-fine-line-between-stupid-and-clever/

https://ericsonyachts.org/ie/ubs/how-to-remove-a-sailboat-engine.903/

 

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2 hours ago, Zonker said:

Can't say I agree with cutting up the grid. He might not know how it is built - and how he should taper out repair and rebuild it. I know in the Beneteaus they use unidirectional e-glass on the top flange of the grid. You cut that, you really need to replace it with uni, not just some biaxial or double bias.

Even though it costs more epoxy is just so much better for structural repairs. Compared to the cost of the boat, what's a thousand dollars extra for epoxy?

Be curious how many gallons of resin Expedition Evans used for their repairs. 

Secondary bonding is really poor with polyester, especially the DCPD resins (I would assume) these guys use.  As Zooker says….epoxy seems a minor extra expense for a much better repair

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Well, if you’re a big company, cutting a few minor extra expenses on each job (but charging just as much for the job) adds up to a nice bonus for the executives at the end of the year.  

Now, for the advanced class, we’ll discuss “softening” the difference between direct and indirect expenses...

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Well I finished it. (top tip, set the playback speed to 1.25 or 1.5 and pause at the more interesting bits)

I'm not sold on the whole polyester thing, but it does seem that the yard does a hell of a lot of these, and judging from the amount of laminate added it looks like they went for the belts & braces approach. 
image.thumb.png.ccc9519242aa6a5fa7147b9ce829178d.png
 

7 hours ago, Zonker said:

 I know in the Beneteaus they use unidirectional e-glass on the top flange of the grid. You cut that, you really need to replace it with uni, not just some biaxial or double bias.

Even though it costs more epoxy is just so much better for structural repairs. Compared to the cost of the boat, what's a thousand dollars extra for epoxy?

I'm guessing the uni across the top must be fairly common? I got the lay up scedule for my boat from the designer and the tops of the floors have 4 layers of 600gsm UR before the last finish layer of CSM. 

One thing I saw he did was using a polyester bonding paste from Crestafix to help with adhesion for the first layer of matt, Have you heard of that practice before @Zonker?

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9 hours ago, TwoLegged said:

Ah, I missed that.  What a scummy practice.  It makes buying a Beneteau (new or used) into a massive risk.

Is Hanse any more forthcoming?

Couldnt say but Hanse's model is you never speak to the factory the dealer does everything?


I can see why the insurance industry wants the manufacturer to be involved in the repair as when the keel falls off its tends to kill people and we now have a history where poorly repaired grounding damage has failed and killed people.
My guess in these cases is  the extent of the damage was never properly determined so there was a smaller repair than required done?
Putting the same glass back and doing a poly over poly repair is weaker than the original is that an issue?
Where is the science to say how much extra poly to make an existing poly layup as good as it was before?

Should the insurance industry say a grounding repair must be done using epoxy? Where are the manufactures putting their engineering skills on the line here to give repairers advice?

If the grid has cracked should the whole grid be cut out and factory sends you a new one?


I am not sure that ultra sonic testing of laminates is an absolute science?

In my other life I race powerboats, plenty of people buy old boats and go fast and there have been some spectacular structural failures as clearly the slamming effect over years delamed the boat but you cannot see it even in hulls where the inside is left un coated just for that purpose. ( and save weight)

Does a grounding do the same damage as years of go fast slamming?

 

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10 hours ago, MiddayGun said:

I'm guessing the uni across the top must be fairly common?

Likely - but no direct knowledge.

10 hours ago, MiddayGun said:

sing a polyester bonding paste from Crestafix

Odd. Not sure why that would be any different than mat + laminating resin. Maybe just to fill in lumpy bits at the edge of the grid.

 

8 hours ago, Sailabout said:

Where is the science to say how much extra poly to make an existing poly layup as good as it was before?

"Eh that looks about right"

8 hours ago, Sailabout said:

Should the insurance industry say a grounding repair must be done using epoxy?

The insurance industry is remarkable in it's lack of knowledge of boats. They are $$ people. As long as the cost of claims << amount of premiums they probably don't care if you fix it with cardboard and it's deratives! 

8 hours ago, Sailabout said:

If the grid has cracked should the whole grid be cut out and factory sends you a new one?

Probably that does mean a total scrapping of the vessel because you have to remove engine and much of the interior. The labour hours would eat up the cost of the vessel. I think a decent repair can be done in-situ. I do think vessel builders should provide repairers the laminate schedule of the existing grid. It's not really top secret.

They will not want to design a repair for you, because each damage is going to be different and you can't necessarily see all that has failed.

Even if they went back to laminating individual transverses of plywood and tabbing them in, the damage would be similar (cracked transverses and broken tabbing) and you'd have to grind back the tabbing and replace the transverse.

8 hours ago, Sailabout said:

I am not sure that ultra sonic testing of laminates is an absolute science?

It's not what I would use. Think of ultrasonics as like a depth sounder. It sends out a beam, hits something and reports back the depth. In a metal you're looking for hidden cracks. If the metal is 1cm thick and the ultrasonic shows a spike at 0.4cm, then you have *something* there. 

With a laminate, each layer is a little discontinuity - and thus may reflect the beam. I don't know how much ultrasonics are used in composite NDT.

Thermal imaging is more common and does a good job of revealing defects.

8 hours ago, Sailabout said:

Does a grounding do the same damage as years of go fast slamming?

Not quite. A grounding is one big spike. Years of go fast slamming is cummulative damage (micro cracking of the resin) and is more fatigue related and probably over a wider area. Unless you go over a monster wave that is much bigger than the powerboat is designed do. Then it's a big spike

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11 hours ago, MiddayGun said:

Well I finished it. (top tip, set the playback speed to 1.25 or 1.5 and pause at the more interesting bits)

I'm not sold on the whole polyester thing, but it does seem that the yard does a hell of a lot of these, and judging from the amount of laminate added it looks like they went for the belts & braces approach. 
image.thumb.png.ccc9519242aa6a5fa7147b9ce829178d.png
 

Wow - nice work. That looks like it came out of a mould.

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4 hours ago, Zonker said:

High gloss paint can make things look good if you don't stand too close I think

And filler. Lots of filler.

FKT

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Its actually gelcoat and surprisingly very little filler.

The workmanship itself looked to be pretty good with regards to the glass work & the the keel alignment, its just if the new laminate itself is up to the job, there's certainly a metric shitload of extra glass been added. 
According to the video the yard have done a lot of these repairs now (signs of the times I guess) and whenever they've grounded again hard they usually break in a different spot. 

I guess Swedish groundings are a pretty extreme since its all just rocks around there. 

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40 minutes ago, Sweare Deep said:

A cast iron keel with an almost vertical leading edge hitting a rock seems like a good recipe for problems somewhere in the structure.

I have never understood why nobody seem to have tried putting some sort of crumple zone on the leading edge of fin keels.  Whether it's a crunch-and-replace structure or a rubbery layer which would be expected to recover from most impacts, anything to reduce the sharpness of the initial impact would help a lot.

The only boat I have ever seen with anything remotely like that was on a design which didn't really need it: the later versions of the old long-keeled 27-foot Kerry sloops, which had a lead cone at the front edge of the keel.  That softened the impact a bit when rock-hopping.

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44 minutes ago, TwoLegged said:

I have never understood why nobody seem to have tried putting some sort of crumple zone on the leading edge of fin keels. 

hmmm . . an option if you are inclined to worry about these sorts of things is to get a (decently built) metal boat.

We wacked rock ledges with the bottom tip of our rudder and a sunken concrete retaining wall (which navionics had left off their chart) with our keel, and just sailed away (a little dent here or there).

The majority of keel hits I have seen have been on the tip of the keel, and a lead bulb actually does a decent impact absorption job, and the ding can usually just be hammered out. But yea from an engineering standpoint some sort of energy absorption zone would make sense - I guess I would prefer one that 'bounced back into shape' (eg like rubber) than one which needed to be replaced (eg like foam or car bumper).  But it would seem the market does not think it is worth the price -

 

------------------------------------------------------------

I am curious whether french production boat building has gotten worse over the past 20 years?  BENETEAU used to have some models that were reasonably respected (given they were inexpensive production) for offshore use. They had some weaknesses (strong autopilots used to rip aft bulkhead unless beefed up) but my impression was they were higher quality that what we have seen above (in even the ones people say are 'better' which still look like crap to me).

 

 

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On the other end of the spectrum in design and construction standards you can find both a sacrificial laminate on  the leading edge of the keel and the notion of a 'crashbox', where the keel bolts, in this case pins, are placed within a sealed aluminum box and the leading pin is a sacrificial fuse pin, meant to breakaway in the event of catastrophic impact. 

When people think of kevlar as an impact resistant laminate, they are not generally thinking of it as 'absorbing' impact, which in this case, when the kevlar is placed between the outer carbon layer and the inner core, is exactly what it's doing. Its not a rubber bumper, but it's meant to do a similar job.

You can read about the construction details of both the kevlar laminate crash barrier on the leading edge of the keel, and the crashbox, here in Bill Lee's technical review of Bieker's Riptide 55.

https://svrocketscience.com/technical-details/

 

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2 hours ago, estarzinger said:

hmmm . . an option if you are inclined to worry about these sorts of things is to get a (decently built) metal boat.

Yeah, in theory.  But in practice, while metal boats are of course better able to survive to impact, there are few metal boats available in the popular sizes and types.  Metal costs more to mass produce than brittle GRP, and it leaves a bit less room for the vast wide saloon that the current market demands.

So custom-builders like you and Beth increasingly go for metal, esp for high latitudes ... but yer mon+pop+kids looking for 5–10 yo coastal cruising are looking at a market that's supplied 99% with various flavours of GRP, and I don't see that changing.

2 hours ago, estarzinger said:

The majority of keel hits I have seen have been on the tip of the keel, and a lead bulb actually does a decent impact absorption job, and the ding can usually just be hammered out. But yea from an engineering standpoint some sort of energy absorption zone would make sense - I guess I would prefer one that 'bounced back into shape' (eg like rubber) than one which needed to be replaced (eg like foam or car bumper).  But it would seem the market does not think it is worth the price

Better engineering of production boats would of course be great.  But while lamination quality as improved a lot in the last two decades thanks to vacuum bagging, many of the gains have been sacrificed by the adoption of the cost-cutting glued-in-grid.

I think that a rubber-like leading edge on the tip could be implemented quite cheaply: it costs no more to make a keel mould designed for that than to make one without, and the moulded rubber infill shouldn't cost more than low hundreds.  But those low hundreds of dollars would win far more sales if placed in the interior, and bump-protection would be hard to market.  The message could easily come across as "hey, idiot customers who drive yer boats into rocks! Our new feature makes it a wee bit less likely that your idiocy will completely destroy our fragile boats".

2 hours ago, estarzinger said:

I am curious whether french production boat building has gotten worse over the past 20 years?  BENETEAU used to have some models that were reasonably respected (given they were inexpensive production) for offshore use. They had some weaknesses (strong autopilots used to rip aft bulkhead) but my impression was they were higher quality that what we have seen above (in even the ones people say are 'better' which still look like crap to me).

It seems to me that the market has changed a lot.  Charter has taken off, thanks to cheap flights and low interest rates to finance the charter fleets.  So a large chunk of Beneteau's market is charter fleets, who have less interest in long-term durability.

Meanwhile, the cruiser-racer market which dominated in the 1970s and 1980s, has almost vanished.  Racing itself has been professionalised and dominated by more extreme boats, and changing family dynamics mean that a boat purchase needs to be more family focused.  The money no longer goes into sail wardrobes and winch farms and multiple headsail tracks; it goes to the cockpit table and swim platform and the fancy saloon plus ensuite cabins.  Those customers are being served by the cast-offs of the charter fleets, which are fairly good fit for their wants tho maybe not their needs).

So the charter fleets are driving the market.

Plus, that market is shrinking.  Most of the middle class has less spare time, and spiralling housing costs leave them with less spare capital.  A few at the top have more cash, so the market for 50-footers is healthy, but the days when doctors and dentists were running cruiser-racers is over.

Those who do buy cruiser-racers still have French suppliers.  JPK builds very well-engineered boats, as does Pogo Structures.  J-Composites seems to me be offering significantly lower quality of engineering than JPK or Pogo, but it's in a similar market-space to where Beneteau's First line was in the 1980s.

 

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3 hours ago, estarzinger said:

I am curious whether french production boat building has gotten worse over the past 20 years?  BENETEAU used to have some models that were reasonably respected (given they were inexpensive production) for offshore use. They had some weaknesses (strong autopilots used to rip aft bulkhead unless beefed up) but my impression was they were higher quality that what we have seen above (in even the ones people say are 'better' which still look like crap to me).

I don't think builders used particle board covered with plastic laminate for furniture 20 years ago.

My early 80's Hunter had marine plywood everything.

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1 hour ago, TwoLegged said:

So custom-builders like you and Beth increasingly go for metal, esp for high latitudes ... but yer mon+pop+kids looking for 5–10 yo coastal cruising are looking at a market that's supplied 99% with various flavours of GRP, and I don't see that changing.

Why buy a Land Rover when a minivan is what you need?

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The newer, wider hull shapes that production builders are pouring out have big, flat areas along the centerline - which are much easier to dimple than the older hulls with curved sections

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4 hours ago, estarzinger said:

I am curious whether french production boat building has gotten worse over the past 20 years?  BENETEAU used to have some models that were reasonably respected (given they were inexpensive production) for offshore use. They had some weaknesses (strong autopilots used to rip aft bulkhead unless beefed up) but my impression was they were higher quality that what we have seen above (in even the ones people say are 'better' which still look like crap to me).

yes, you're correct. Early / mid 80's Firsts were well built, as was Jenneau which were stick built before taken over by Beneteau. But the focus was on cost, not strength or durability.

We had foam crash bows on our cat because it's easier to build them that way on a one off. They took a hit, crumpled a bit but the solid laminate 4" aft were undamaged. At haulout, glue in a bit of foam to replace the missing / crushed stuff, a few light layers of glass and then some antifouling. Really liked it. Not all owners are as comfy doing this sort of repairs but we did it once at Chagos (ssshh) at low tide on a beach. Took less than an hour.

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Sounds great, @Zonker.  And naughtiness by you in repairing your vessel is a drop in the ocean compared to what the colonial power did there.

So we have two few examples of simple crash protections which are quite cheap to add, but not free.  And which don't happen on production boats, because interior comfort is easier to sell.

It was similar with motor cars.  Crash protection and other safety features was driven by legislation, because with a few honourable exceptions like Merc and Volvo, the makers were happy to sell avoidably dangerous cars.   Production boat builders don't need to go full (Volvo) Ocean Race to make their boats a wee bit more durable, but  it would probably take external pressure to get them to shift ... and there's no sign of that pressure.

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I did not drop any epoxy into the ocean. Just some sand was squished. OK maybe some fiberglass dust was created. This was the same island where we pulled the rudder from a 48' boat that had gone on a reef and fixed it ashore.

It would be smart to laminate up a small part of the grid at the back of the keel as a separate member with flanged/bolted joints to the main grid. That's the part that generally fails in a hard grounding. So when it does fail, you unbolt it, grind away the bonds holding it to the hull and glue in a new one. Make the main grid forward and outboard a bit stronger so the shock loads don't break it.

As a research project you could get a insurance/salvage boat that had experienced these type of failures, cut away the failed part, install in a new separate bolted part, and then deliberately ram it into a concrete block underwater and see if my idea works.

But cost prevents this.

image.png.0bfa4e8329a3b79fae8106dab6f6692b.png

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1 hour ago, TwoLegged said:

It was similar with motor cars.  Crash protection and other safety features was driven by legislation, because with a few honourable exceptions like Merc and Volvo, the makers were happy to sell avoidably dangerous cars.   Production boat builders don't need to go full (Volvo) Ocean Race to make their boats a wee bit more durable, but  it would probably take external pressure to get them to shift ... and there's no sign of that pressure.

The body count from recreational sailboat keel failure/grid separation is ... ??? ... non-zero, but very low. I would wager more people are crushed by pianos every year than die from major structural failure in late-model composite sailboats. So that's one qualitative difference from the sphere of automobile safety. The real complaint with this grid/pan/liner construction is that a mid/high-probability event (hard grounding during coastal racing or cruising) totals the boat, making it uneconomic to repair properly and perhaps uncertain what a proper repair even looks like.

That's not so different from today's modern, much-safer automobiles. Airbags, crumple zones, sacrificial bumpers, thinner sheet metal, unfixable plastic bits, unibody construction: some of these construction methods keep car prices affordable or manufacturers profitable; some contribute to a car's energy-absorption in a crash. ALL make it harder and more expensive to repair a car after even a rather modest impact. If you skid your 2017 Camry into a bollard at 20mph, crumple the hood or front quarter panel, deploy one or more airbags, and bend the steering arm, don't be surprised if the repair bill is roughly 1.5x book value and the insurance company declares it for salvage. 

There are people who buy up these salvage vehicles, rehab them (some competently and honestly, some not), and sell them at close to book value. Glad that is not my job!

 

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37 minutes ago, Zonker said:

I did not drop any epoxy into the ocean. Just some sand was squished. OK maybe some fiberglass dust was created. This was the same island where we pulled the rudder from a 48' boat that had gone on a reef and fixed it ashore.

So you are an unrepentant sand-squisher, @Zonker.  Shocking eco-vandalism ;) 

Your experiments sound like a good idea.  It might not be that expensive if you took some hurricane write-offs, and got sponsorship to do it in the style of Yachting Monthly's 2015 crash test series.

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I shall have to write up a grant application. The EU seems more receptive to that considering how much money they shovelled spent on Nigel Calder's hybrid exercise a few years ago.

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The problem with a rubber leading edge is energy. You have only a few inches of compression to decelerate a 25,000 lbs boat. The forces developed in the keel root aren't going to change much. Best way to deal with it cheaply is to get away from the ridiculously narrow chords in keel roots. This is a racing affectation, with unmeasurable affect on cruising boat performance. If you taper the keel root to get say twice the chord at the root, you have 1/2 the forces and 1/4 the deflections. 

However most of these production boats are built to sell, not to sail - and certainly not to ground. 

Many years ago Swan in conjunction with a university instrumented the laminate and ran a sailboat deliberately into hard stuff. The result was that stresses were higher than originally thought. But like many similar efforts, the conclusions were ignored.  

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1 hour ago, DDW said:

Best way to deal with it cheaply is to get away from the ridiculously narrow chords in keel roots. This is a racing affectation, with unmeasurable affect on cruising boat performance. If you taper the keel root to get say twice the chord at the root, you have 1/2 the forces and 1/4 the deflections.

Exactly right. My old Columbia 43 keel had a very wide flange that sat in a moulded in rebate in the hull with parallel rows of bolts on 12" centers. It had hit something coral?) hard enough to gouge 1/4" deep scrapes in the toe of the iron keel and there was zero damage.

 

9a Keel prepped for mounting.JPG

9b Keel prepped for mounting.JPG

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11 hours ago, estarzinger said:

hmmm . . an option if you are inclined to worry about these sorts of things is to get a (decently built) metal boat.

We wacked rock ledges with the bottom tip of our rudder and a sunken concrete retaining wall (which navionics had left off their chart) with our keel, and just sailed away (a little dent here or there).

Yeah. It's why I built my own.

So far the worst thing that's happened is, I've needed to apply more epoxy on the 40mm thick keel shoe a couple weeks ago while on the hard.  Fair bit of paint missing and I know where it is. This is sufficient of a PITA to get me to think twice about just how shallow the water really is, but otherwise - pffft. Not going to damage the boat in the slightest.

FKT

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5 hours ago, DDW said:

Best way to deal with it cheaply is to get away from the ridiculously narrow chords in keel roots. This is a racing affectation, with unmeasurable affect on cruising boat performance. If you taper the keel root to get say twice the chord at the root, you have 1/2 the forces and 1/4 the deflections.

The force is the same. You've just spread it out a bit wider. But the main problem isn't the width of the impact force. It's how non-damage tolerant the inside structure can be.

You would not be happy if a 5 mph collision totalled your car. We have bumpers and crash structures designed to absorb minor impacts. A 6 or 7 knot impact of a keel onto something hard can total boats with integral bottom grids.

If you had a crash structure (galvanized steel for argument) that was strong and stiff enough to spread the initial impact out further into the glass keel grid you might be able to dissipate it without failure.

Cast iron keels don't help. They're very stiff compared to lead ones. 

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15 minutes ago, Zonker said:

If you had a crash structure (galvanized steel for argument) that was strong and stiff enough to spread the initial impact out further into the glass keel grid you might be able to dissipate it without failure.

Isn't that what X-Yachts does?  https://www.google.ie/search?q=grid+site%3Ax-yachts.com

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21 minutes ago, Upp3 said:

Salona does that too. I find it funny that their standard keel (at least in 38) is bulb and performance is just a fin and their draft is the same.

523581728_Salona38profile.thumb.png.1ce485b8c7ace3f9f1d8c1705f3622c3.pngUnfortunately, the Salona 38's bulbed keel is of the torpedo type.  It's not an extreme torpedo, but there is still enough protrusion ahead of the fin's leading edge to snag pots and lines and kelp and so on.

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9 hours ago, Zonker said:

You would not be happy if a 5 mph collision totalled your car. We have bumpers and crash structures designed to absorb minor impacts. A 6 or 7 knot impact of a keel onto something hard can total boats with integral bottom grids.

The 5 mph car crash is the equivalent of a marina scrape. 6-7 knots is a top speed motorway smash in cruising land.

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36 minutes ago, Snowden said:

The 5 mph car crash is the equivalent of a marina scrape. 6-7 knots is a top speed motorway smash in cruising land.

Yeah the grid in my boat was built the old fashioned way, but I can't imagine coming away without significant damage if I ploughed into a rock at 7 knots, despite the lead keel. 

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Here's a picture of a sistership after a 9kt meeting with some rocks.  I'm impressed they got it moving that fast. Must have had some tide for help. 

hull_damage_01.jpg.10b72f98af0b6662184a451462e663af.jpg

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Yeah X yachts does that. I'm sure it costs more than the Beneteau's molded grid. I was suggesting a hybrid. Steel in the high load area; connected to a glass grid further outboard and forward.

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https://money.cnn.com/2007/08/01/autos/iihs_luxury_bumper/index.htm

https://www.wired.com/2001/07/suv-bumpers-fail-5-mph-test/

Over $5000 USD in damage in 5mph bumper tests.  And those were the days (2001) when most compact SUVs were body-on-frame. It has only gotten worse since then. The current US standard is 2.5 mph with no structural damage. Many cars don't even meet that standard, per insurance industry trials.

I agree with Snowden that 6kts is near the top of a cruising boat's speed range; that a yacht, while slower than a car, is generally much heavier; and that the lever arm of an appendage makes the engineering hard. Bristol Channel Cutters remain an option for buyers strongly averse to keel grounding damage.:lol:

 

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6 minutes ago, Zonker said:

Yeah X yachts does that. 

The X's steel grid have not aged all that well - or at least many of them I have seen - rust/corrosion and relatively hard remove to proper fix.  Not necessarily a concept flaw, but rather the implementation could have been done rather better.

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11 hours ago, Zonker said:

The force is the same. You've just spread it out a bit wider. But the main problem isn't the width of the impact force. It's how non-damage tolerant the inside structure can be.

The forces (and stresses) at the leading and trailing edge of the wider keel root are 1/2. The total impulse and moment are the same. The supporting structure must be able to absorb this impulse without damage in my opinion, not be damage tolerant. Obviously there is always a speed of impact that will exceed the structures ability to absorb it. In this case a very large section of the bottom should be ripped out of the boat (and it will be truly totaled), not the sort of localized damage we are seeing from these modern keel removals. The Hanse is "damage tolerant", if that is defined as something fairly easily repaired as shown in the video - the keel mounting is a brittle fuse. Not a great idea, if you are further from land than you can swim. 

I would not buy a boat with a galvanized steel grid embedded in the hull - that is just a time bomb in my opinion. 

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26 minutes ago, Diarmuid said:

Bristol Channel Cutters remain an option for buyers strongly averse to keel grounding damage.:lol:

It's not clear whether the Bristol Channel Cutters' ability to survive a grounding is due to impact resistance or to the lack of velocity in non-gale conditions :) 

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7 minutes ago, estarzinger said:

The X's steel grid have not aged all that well - or at least many of them I have seen - rust/corrosion and relatively hard remove to proper fix.  Not necessarily a concept flaw, but rather the implementation could have been done rather better.

It is much easier to spread the load in the keel itself - either a wider root or embedded well up into a hull socket - than in the bottom of the boat, which is usually a large pretty flat surface, and in modern shapes cannot have much depth. 

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20 minutes ago, TwoLegged said:

It's not clear whether the Bristol Channel Cutters' ability to survive a grounding is due to impact resistance or the lack of velocity in non-gale conditions :) 

Low speed, long keel, steep sides, roughly 30% interior volume given over to framing members.... 

We can learn much from gothic architecture: A tapered vertical pillar rising from the aft corner of the keel/hull join, branching out into vaulting and fornication on the deck undersides. Exterior buttressing may cause drag at certain heel angles, tho....

GettyImages-1045543026-6eca41298ad543ac896f904caa5dec92.jpg

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25 minutes ago, DDW said:

It is much easier to spread the load in the keel itself - either a wider root or embedded well up into a hull socket - than in the bottom of the boat, which is usually a large pretty flat surface, and in modern shapes cannot have much depth. 

Interestingly (or perhaps not lol) Van De Stadt designed Hawk's keel using a 'socket' like structure.  The keel envelope and structural beams inside it were brought up about a foot into the boat - not just welded to the bottom, and then that 'socket' was tied to whole boat structure with ring frames - notably very big ones at mast and chainplates and aft end (but also lots of smaller ones).  We had more hull/bilge depth than a really modern light weight boat, but rather less than an older 'traditional' design.

I rather suspect the French production builders are still convinced their keels and interior grids are 'fit for purpose'.  I rather suspect they would have to take either a huge hit in PR reputation (like the lagoons are) or a huge hit to used boat valuations/insurance willingness to cover before they changed it.

 

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Socketed keels on glass boats make sense too. Carry the fin up into a socket.

I was always suspicious of X boats grid. Evans, do you know if they were fully encapsulated or just the bottom flange of the I-beam was glassed to the hull?

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16 minutes ago, DDW said:

It is much easier to spread the load in the keel itself - either a wider root or embedded well up into a hull socket - than in the bottom of the boat, which is usually a large pretty flat surface, and in modern shapes cannot have much depth. 

A keel embedded into a hull socket is also also a much better way of handling to routine lateral loads of the keel.  The dominant style of vertical bolts into the narrow keel root is like securing the mast with only vertical bolts through the heel of the mast, and no stays.

1693783286_Rival36interior.thumb.jpg.e862e1390ba8f8aeb4cc3c5d657a042c.jpgI'm not so sure that depth is a huge impediment.  Modern boats tend to have a lot of headroom, often to absurdly unseaworthy levels.  A few extra inches in the height of floors would be a huge gain.  But that's not the only way of engineering some strength.  Full-height bulkheads at the fwd end of the galley could also add a lot of strength, as in the Rival 36 pictured right.  The only reason for not having those bulkheads is that unseaworthy loft-style interiors have become a fad for boats which are sold primarily for their non-sailing attributes.

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27 minutes ago, Diarmuid said:

Low speed, long keel, steep sides, roughly 30% interior volume given over to framing members.... 

We can learn much from gothic architecture: A tapered vertical pillar rising from the aft corner of the keel/hull join, branching out into vaulting and fornication on the deck undersides. Exterior buttressing may cause drag at certain heel angles, tho....

GettyImages-1045543026-6eca41298ad543ac896f904caa5dec92.jpg

I wouldn't want the job of scraping the old antifouling off that ;) 

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20 minutes ago, Zonker said:

I have designed boats where the grounding speed was 12 knots. We expected no damage at speeds below that.

it just costs more.

In the case of yer contemporary style mass market yacht, I doubt that the extra costs would be huge.  On a boat selling for say €200K, a 10% increase in price would allow an extra €20K for structure, which would be a huge boost to that budget.

It seems to me that the barrier to stronger build is not so much cost as build process and design.  The mass market boat now seem to be built like caravans, where the furniture is non-structural; the HunBenJanBav-style boat basically has flimsy furniture modules dropped onto .  Reverting to the use of structural furniture (more bulkheads, structural seat fronts etc)would require a change in manufacturing approach ... and a shift away from the loft-style interior with its unseaworthy open spaces.

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43 minutes ago, Zonker said:

if they were fully encapsulated or just the bottom flange of the I-beam was glassed to the hull?

They have had a couple iterations and I dont know the details of all the variations - but the ones I have seen were not fully encapsulated - you could see metal.

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As I understand it, Francis Lee has a substantial structure to transfer the keel loads into the hull.   Maybe

@kimbottles will chime in on the design and cost aspects of this most excellent feature.

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2 hours ago, TwoLegged said:

It's not clear whether the Bristol Channel Cutters' ability to survive a grounding is due to impact resistance or to the lack of velocity in non-gale conditions :) 

The Bristol cutter would need to be designed to take an impact because by the time you've seen something you're probably going to hit it.

Since I spent a week on a gaff rigged cutter I now give them a lot of space.

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23 minutes ago, European Bloke said:

The Bristol cutter would need to be designed to take an impact because by the time you've seen something you're probably going to hit it.

Since I spent a week on a gaff rigged cutter I now give them a lot of space.

Yes, directional stability has its downsides

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1 hour ago, slap said:

As I understand it, Francis Lee has a substantial structure to transfer the keel loads into the hull.   Maybe

@kimbottles will chime in on the design and cost aspects of this most excellent feature.

Substantial is an understatement. There are photos in the Project Sliver thread but I'm damned if I can find them.

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19 minutes ago, IStream said:
2 hours ago, slap said:

As I understand it, Francis Lee has a substantial structure to transfer the keel loads into the hull.   Maybe

@kimbottles will chime in on the design and cost aspects of this most excellent feature.

Substantial is an understatement. There are photos in the Project Sliver thread but I'm damned if I can find them.

AFAICR, one the key aspects of the design of Francis Lee is that the bunk fronts are structural components of the keel load system.  That roughly-18-inch-high, 6'6" long vertical component massively strengthens the whole system when compared with the flat grid structure used in production boats.

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3 hours ago, estarzinger said:

They have had a couple iterations and I dont know the details of all the variations - but the ones I have seen were not fully encapsulated - you could see metal.

Another Scandinavian yacht builder thought putting galvanized steel in a sailboat bilge was a good idea. Here's the original mast support truss from our 1972 Albin Ballad:

trussrot1.JPG.7b28fe27df94020d7077c9de7fa500eb.JPG

trussrot2.JPG.dbd2ae03760a2e4a11cae10b8a969ab9.JPG

The bottom 7/8ths was encapsulated in polyester resin, and this boat lived nearly all its life on Lake Michigan.

The replacement is thicker, 316 stainless, and only the foot is bedded in resin. The rest is free to drain and air-dry. :)

 

nutruss5.JPG.2b434893d2e77f73420ea634a2a94080.JPG

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FRANKIE’s keel structure was designed by Tim Nolan who is a very experienced and talented Marine Engineer who is a graduate of the University of Michigan School of Naval Architecture and Marine Engineering. He is well known for engineering mega yachts and naval vessels at Tim Nolan Marine Engineering in Port Townsend, WA.

https://name.engin.umich.edu

My instruction to Tim was simple: “I never want my keel to fail.”

So he designed a keel system that is extremely strong. The lead bulb is bolted onto the steel fin and then the fin is bolted through the solid glass keel bed into a water jet cut and welded 316 Stainless Steel I-beam grid that is then bolted onto two solid girders (think G-10) that run the length of the interior from the galley to the berth forward. Every bulkhead, berth and settee front and flat is tabbed into each other and into the girders so the entire interior of the boat is one solid monocoque structure which is tabbed strongly into the deck and hull. It acts as one big box structure.

The girders are heavy as hell.

When we pumped the mast jack up to 5000 pounds we heard nothing, not a sound. It was kind of spooky. The chain plates are bolted into a solid (not cored) bulkhead (think G-10 again) and are titanium. The mast step is also water jet cut and welded 316 SS I-beams and is of course bolted onto the girders.

All the bolts are Aquamet 22 a very strong type of stainless steel.

So far we have not seen any movement anywhere in FRANKIE’s structure. (And we have sailed her pretty hard a couple times to weather.)

Here are pictures I posted sometime ago on the Sliver Project Thread. Our keel system is pretty stout. (I don’t remember how much all this cost, but it wasn’t cheap by any means. But then FRANKIE wasn’t cheap to build. No properly designed and engineered custom boat is ever cheap. We cut no corners on FRANKIE as I expect our two sons to use her after I am gone.)

42CB6AD2-AC54-44D3-B156-0997CD1F9D84.jpeg

2230822D-B721-40A0-8651-9C89E1747240.jpeg

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1 hour ago, Zonker said:

Kim is the s.s. grid laminated in any way or is it all bolted to the bunk fronts/bulkheads?

It is bolted. I will take a picture of the backing next time I row out to the moorings. The bolts go into the girder and the girder is tabbed into the hull, bulkheads and settee/berth flats. The girder makes up the settee fronts.

The design is a work of art. Tim gave me a thick notebook of all his calculations and drawings.

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Bolting the welded 316 grid onto G10 laminated into the structure is a good plan. However for Hanse and Beneteau, this isn't on the menu. They could however, increase the layup by 2x in the affected areas, and tab the grid to the hull rather than float it in some spooge. The difference in cost is no where near €20K and probably well less than €2K. They don't do it because no customer asks for it, and rarely have a problem because most of these boats rarely leave the marina. They keep the €2K in their pocket. 

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8 hours ago, Diarmuid said:

We can learn much from gothic architecture: A tapered vertical pillar rising from the aft corner of the keel/hull join, branching out into vaulting and fornication on the deck undersides.

I never even attempted fornication on the underside of any deck.

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2 hours ago, DDW said:

Bolting the welded 316 grid onto G10 laminated into the structure is a good plan. However for Hanse and Beneteau, this isn't on the menu. They could however, increase the layup by 2x in the affected areas, and tab the grid to the hull rather than float it in some spooge. The difference in cost is no where near €20K and probably well less than €2K. They don't do it because no customer asks for it, and rarely have a problem because most of these boats rarely leave the marina. They keep the €2K in their pocket. 

This.  We all love to blame the builders and/or designers, but ultimately aren't we (the owners and skippers) ultimately responsible?  What sells today is a floating condo with heat/ac, two heads with separate shower stalls, at least 3 "staterooms," an oven and microwave, etc, etc.  No one cares if it doesn't have a nav station, or can actually sail upwind (who does that these days?)...they couldn't really care how the keel was attached, or the mast held up, etc, as long as the electric winches will pull the sails around with a push of a button, and I have thrusters fore and aft 'cause I don't actually have any in close maneuvering seamanship skills so can't dock the damn thing without them.

If we insisted that we cared more about build quality, and keeping the keel attached with little to no damage after a grounding, I'd have to think they'd build us that boat.  But we don't...

Sigh....:(

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2 hours ago, SloopJonB said:

I never even attempted fornication on the underside of any deck.

The Royal Navy would like to extend an invitation....

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2 hours ago, Crash said:

No one cares if it doesn't have a nav station, or can actually sail upwind (who does that these days?)...they couldn't really care how the keel was attached, or the mast held up, etc, as long as the electric winches will pull the sails around with a push of a button, and I have thrusters fore and aft 'cause I don't actually have any in close maneuvering seamanship skills so can't dock the damn thing without them.

So - you've seen me getting in & out of the Travel lift then?

Except we don't have push-button anything. Just the lack of close maneuvering seamanship skills. Fortunately plastic boats make good soft landing pads.

In fact I agree with you WRT modern boats. After looking at a lot some 15 years or more back I concluded that the majority weren't really designed to actually *sail* anywhere let alone in adverse conditions. They were designed to move from marina to marina with a big cockpit for max entertainment potential while moored or in a pen. Works just fine in places like Sydney where the max distance they usually move is to Pittwater and back again.

Friends tell me that the shit-fights over the public moorings in summer or public holidays is truly amazing to watch. Heaven forbid they anchor.

But yeah - these grid fail issues are purely marketing choices pushed down onto the engineers. The engineers all know how to do it better but they're not permitted to do it; no real blame attaches to them IMO. So nothing is going to change until marketing changes.

FKT

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From Hanse's own website on the 418...

Hanse 418 cockpit | All the halyards lead to the helmsman. This gives you absolute control in all sailing manoeuvres. | Hanse

Hanse 418 bathing platform | The spacious cockpit and the inviting bathing platform let you revel and relax in pure sunshine. | Hanse

Hanse 418 exterior | The interplay of a perfectly adapted lateral plan and a pre-balanced rudder blade is your guarantee for fantastic speed, stability and safety. | Hanse

This last pic is the "sportiest" set of wind and sea conditions they show the boat sailing in, every other "sailing" pic is more benign...they aren't even trying to appeal to "sailors." They are appealing to folks who want to live a "lifestyle."

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9 hours ago, SloopJonB said:

I never even attempted fornication on the underside of any deck.

It generally requires the vessel be inverted or that you have velcro on your knees or a can of anti-gravity...

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1 hour ago, Jim in Halifax said:
10 hours ago, SloopJonB said:

I never even attempted fornication on the underside of any deck.

It generally requires the vessel be inverted or that you have velcro on your knees or a can of anti-gravity...

Maybe the flimsy keel mounting is designed to help with the inversion needed to allow deck-underside fornication?

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Malaya's mast step prior to the cleaning, painting and re-bedding of the aluminum shoe. The keel at this station is a laminate apx. 20" across by 10' depth.

 

20160220_125003.jpg

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12 hours ago, Crash said:

 

If we insisted that we cared more about build quality, and keeping the keel attached with little to no damage after a grounding, I'd have to think they'd build us that boat.  But we don't...

Sigh....:(

Sure they do, they just cost a lot more.

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Of course they do.  That's not unreasonable.  First to put better engineered and stronger, more damage tolerant structure in costs both time and money.  And time costs to, so you have to add that cost. Then, as the market is smaller (both due to the increased cost, and maybe by the compromises required - so loss of "wide open space") the builder has to sell the boat at a higher margin that also adds cost.

As the old saying goes, "you get what you pay for..."

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On 6/17/2021 at 4:11 AM, TwoLegged said:

So we have two few examples of simple crash protections which are quite cheap to add, but not free.  And which don't happen on production boats, because interior comfort is easier to sell.

 

 A third option is to allow the keel to fold rather than being a rigid structure. When looking at the extra cost, I pretty quickly decided it would pay for itself if I ever did have a bad collision. The hydraulics are pretty compact, this is the pump that sits under the end of cabin table, its about the same size as the rubbish bin. 

IMG_2174.thumb.jpg.ffccc67832f6ef6dc01d2d0af784bb89.jpg

 

 

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58 minutes ago, shaggybaxter said:

 A third option is to allow the keel to fold rather than being a rigid structure. When looking at the extra cost, I pretty quickly decided it would pay for itself if I ever did have a bad collision. The hydraulics are pretty compact, this is the pump that sits under the end of cabin table, its about the same size as the rubbish bin. 

IMG_2174.thumb.jpg.ffccc67832f6ef6dc01d2d0af784bb89.jpg

 

 

Does the hydraulic pump have a calibrated blow-off feature, or some other means of absorbing energy? Because liquids are basically as incompressible as solids in a closed system. Seems like it would take one hell of an impact to make a hydraulic ram run backward, unless it was ported for the purpose.

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