WindmanV said..
Gestalt asked : got me thinking whether brass screws for the brass inserts would be strong enough.

By experience, answer is no.

One of the local sailors who knew absolutely nothing about the technical aspects of windsurf boards (but could sell pastries as his normal job), used brass screws on one of his boards after a SS screw failure and they failed under load almost immediately.

Thx
Good to know..

Gestalt said..

lemat said..

Gestalt said..

AI.Dave said..
corrosion and stuck/broken screws with the finer threads and metal to metal contact?

It depends on the type of stainless steel screw being used with the brass. both brass (sanded) and titanium (Flikka) are excellent in saltwater environments. I specify lights for coastal architecture and use a local company that specialises in brass fittings which offer good warranty.everything else just falls off the buildings.

titanium is even better..

the issue is galvanic corrosion between the stainless steel and brass insert.. marine grade 316 is ok but the brass will corrode over time. I think Flikka uses all titanium so that's not going to experience galvanic corrosion. You don't want to use titanium with brass. Flikka also use titanium because it's light.

got me thinking whether brass screws for the brass inserts would be strong enough.

Edit..looks like m6 brass screws are available with hex head. Maybe with deox r81 anti seize.

I done some insert with A4 (marine grade) stainless claw nuts set in forex plate and laminate both side. With A4 screws no problems. Brass insert should work too, it work with fins. With a little neutral grease on screw before set even better. Galvanic corrosion is a far bigger problem with aluminium.

I wouldn't mid trying something like this or the big head fittings but the cost is steep compared to the sanded inserts. FWIW the sanded type inserts are also available eBay for about $3 per plug.

For me those plugs looks good. At least better than chinook plastic one's.

I'm not saying it would be the lightest but I've often thought about using something like a US box track for footstraps. Very fine adjustment and you can replace the threaded component easily.

Keeping with foot strap inserts and interesting using tracks
Specifically metal inserts, Agree use stainless 316 grade.

A long time ago, I built a couple of wave boards (with offset back inserts).
Used furniture inserts into H80 foam then glassed over, a bit of mucking around to stop resin into threads but worked well and so easy to change compared to conventional inserts.

No problem with jumping but 3 years later the corrosion issue!

Gestalt said..
I like the furniture insert idea and the track concept.. fwiw I use silicon to fill boxes and plugs to prevent resin getting in.. front straps specifically on a track is really interesting.. as with all this stuff every decision comes with weight penalties.

stainless is not the best for marine environments. best is titanium, by a long shot. then brass.. i get stainless is stronger than brass but it's also heavier and it rusts.. if you do a deep dive into stainless in marine environments you will see it has a very hectic cleaning schedule or it rusts, tea stains etc. titanium unfortunately is very expensive..

I'm going to try brass inserts direct into hd blocks on my next build.. super light and cheap
psmfasteners.com/product/inserts-for-plastics-m6-x-16-sonic-lok-brass-0-size-16mm-psm8600060x16-slbm6-os-16mm/
www.wkooa.com/product/brass-insert-nuts-for-plastic-blind-knurled/?srsltid=AfmBOordZFQjHGXd-fR_vpBuAIr9v0c5DaSJSQhL-tzPlZS8eZG7AHlW

Brass work well it's easy to find and to work with hand tools. For no rust problems stainless steel must be 316L grade, A4 for screws and must be work with dedicated tools. I see corrosion problems came from use of same tools for working stainless steel and standard steel. Using protective grease for screws is a good habit, even simple vaseline work for that.

Gestalt said..

stainless is not the best for marine environments. best is titanium, by a long shot. then brass.. i get stainless is stronger than brass but it's also heavier and it rusts.. if you do a deep dive into stainless in marine environments you will see it has a very hectic cleaning schedule or it rusts, tea stains etc. titanium unfortunately is very expensive..

Titanium was banned for some uses in big boats decades ago because in practise, it fractures easily with no warning. It's been dropped for most uses, AFAIK, because it doesn't do much that isn't better done with carbon or ss.

There's thousands of boats from the '60s and '70s out there with stainless steel bolts holding multi-ton ballast keels with no problems, normally zero cleaning, and years of living in bilge water. I had the keel bolts from one of my yachts pulled when it was 40 years old and most of them were perfectly fine and the other had other issues. I used to work in the industry and never heard of anyone even considering ti bolts for keels, and can't recall them ever being used for critical rigging areas.

I'm no boatbuilder but looking at the areas where people spend vastly much more cash on building lightweight sailing craft (ie $35,000 for the bare hull of a 17 foot singlehander, or $70,000 for a foiling Moth) it's normally a case of using thin cores of Nomex or high density foam with carbon over the top. High-load areas like the rigging attachments are made up very easily and lightly by using carbon tows (strands) epoxied to the carbon skin. I think my brother's 37 foot catamaran has its rigging loads taken by simple carbon tows, which would weigh a few grammes and take far more load than anything any windsurfer ever felt.

I'm not up on windsurfer sailcloth, but I still find it odd that a 5.7m dacron sail from the original Windsurfer is less than 2kg and therefore dramatically lighter than most modern sails. I've noted before here that I've weighed by yacht, dinghy, cat and windsurfer sails and the latter are far heavier for their area and the claims that windsurfer sails are tougher seems to be complete BS - I don't know anyone who both wavesailed and done a tough Sydney-Hobart would claim that. or anyone who would have wound the tension into an F18 cat rig and then stacked it big time in a blow. There may be very good reasons for the extra weight in windsurfer sails but I do wonder whether the board sails are more driven by marketing than boat sails. Certainly windsurfer sail makers keep on claiming that sails have ever-wider ranges but they also keep on writing catalogues that say you need the same number of sails to cover the wind range as they did decades ago, whereas the yachts that have gone to 3DI or modern laminates are showing that using different modern approaches really can increase sail range.

Chris 249 said..

mathew said..
But big boats aren't weight-constrained so they can use suitable construction techniques.

Windsurf gear is extremely weight-constrained, which limits what we can do to have effective bonding.

Umm, sorry, what? Some big racing boats are arguably more weight-restrained than windsurfers. Supermaxis, for example, have no weight controls and huge budgets so the lighter the construction, the better. Many other classes of big boats arguably have more weight constraints and high tech than boards.

Even where the actual weight is restricted by weight limits, the big boat guys can still spend huge sums in reducing hull weight. More than 30 years ago I was standing on a set of carbon fibre Nomex core pre-preg floorboards that sat over the top of a ton or so of internal ballast, When you put that sort of tech into something sitting 10cm above lead, you're clearly optimising weight distribution.

Would any serious big racing boat be built of thick soft foam and the layups we use in boards? They've been into pre-preg Nomex for decades now.

As an ex-AC builder and having built plenty of other racing/aerospace parts, I can confirm the level of paranoia around weight saving is very real and borderline absurd at times. But you can't deny the results when you get it right, weight savings = top line performance.

Durability and cost of course are very different conversations. Then there's the human factors involved in getting the most out of nice lightweight kit without destroying it with brute force and ignorance.

Chris 249 said..
Would any serious big racing boat be built of thick soft foam and the layups we use in boards? They've been into pre-preg Nomex for decades now.

Yes. Fountaine-Pajot - as a handicap class.

515 said..
I would like to boards go away from EPS which sucks water to closed cell foam.
Hollow boards have a place for race boards.
Been more into winging and a few companies have closed cell foam such as Appletree and PPC.
Talking to a PPC board rider that their hollow race wing boards have a bulkhead, so they don't sink!

Also seen some home builds using Extruded polystyrene, and on the topic of "gassing" reply comment is that pin holes are your friend.

To your point 515 regards hollow boards.. Naish have released hollow foil boards too.. I wonder how much cost reduction is available if the tech can be up scaled

'


article.
www.surf-magazin.de/en/wingsurfing/wing-boards/board-building-hollow-shell-naish-launches-hollow-boards-on-the-market/

Paducah said..

Gestalt said..

515 said..
I would like to boards go away from EPS which sucks water to closed cell foam.
Hollow boards have a place for race boards.
Been more into winging and a few companies have closed cell foam such as Appletree and PPC.
Talking to a PPC board rider that their hollow race wing boards have a bulkhead, so they don't sink!

Also seen some home builds using Extruded polystyrene, and on the topic of "gassing" reply comment is that pin holes are your friend.

To your point 515 regards hollow boards.. Naish have released hollow foil boards too.. I wonder how much cost reduction is available if the tech can be up scaled

'


article.
www.surf-magazin.de/en/wingsurfing/wing-boards/board-building-hollow-shell-naish-launches-hollow-boards-on-the-market/

And at the other, more pointy end, there are experiments with stainless steel/cf composite masts. Not light at all but competitive. I've heard about similar in Moths. Not all edges of the envelope involve small reductions in weight .

3d printing in Ti is a thing now in bespoke bikes. It might be interesting what additive construction techniques might bring our sport.

I built my own mast extensions once from stainless. Was very happy with how it all turned out until I realised it weighed a kilo.
put it in the bin

I guess the issue is stiffness and cost for windsurfers.

im keen to try it too. Interesting but does seem like a lot of work. My next build is a freemove/style board and I'm going to drill the core like tw custom but more like holes in acoustic treatment ie. smaller dia holes spread at equal centres. I saw a similar idea for a strip plank build. Will avoid certain areas and not fully drill trough so bottom has some shape.

That was about 10 years after we did them in California using nomex honeycomb with Carbon Fiber pre preg in an autoclave. Two piece mold and everything precut for layup. Still have one in my garage.

Cost. Foam makes new models easy to produce .. but slight tweaks for costly mould changes made it hard to have a range of hollow boards.

then labour cost maybe for more complex layup, trimming halves and then bonding halves properly.
I think foam sandwich is the best blend of cost vs durability vs ability to change shape if needed and that's why it's prevailed.
I've seen some great DIY hollow boards but I think the current mass production of them is a response to the trendiness of wing / DW and wanting to have something new that the other companies don't have. I hope it doesn't translate to $5000 windsurf boards soon.

Gestalt said..
I guess the issue is stiffness and cost for windsurfers.

im keen to try it too. Interesting but does seem like a lot of work. My next build is a freemove/style board and I'm going to drill the core like tw custom but more like holes in acoustic treatment ie. smaller dia holes spread at equal centres. I saw a similar idea for a strip plank build. Will avoid certain areas and not fully drill trough so bottom has some shape.

I'm getting drillium vibes - a big thing in the 70s and early 80s when it was "cutting edge" to drill out components to save weight. Then we dropped a couple of kilos off the frame and it didn't seem so important any more.

lemat said..

Mark _australia said..
Cost. Foam makes new models easy to produce .. but slight tweaks for costly mould changes made it hard to have a range of hollow boards.

then labour cost maybe for more complex layup, trimming halves and then bonding halves properly.
I think foam sandwich is the best blend of cost vs durability vs ability to change shape if needed and that's why it's prevailed.
I've seen some great DIY hollow boards but I think the current mass production of them is a response to the trendiness of wing / DW and wanting to have something new that the other companies don't have. I hope it doesn't translate to $5000 windsurf boards soon.

That's here, hollow windfoil board 5599 eur = 9157 aud





8

I'd figured the starboard one was going to be expensive, but thats outta control.


formula foil boards are one of those situations where hollow makes sense. They can weigh in quite heavy at the size they are when foam construction is used, and they're hardly in the water.