Protect your daggerboard with a crash bumper

Ian Farrier’s plans provide for a very strong daggerboard trunk that extends all the way through the boat from the deck to the bottom of the hull. The rectangular head of the board fits snugly inside the rectangular trunk, holding the dagger steady under sail. But what happens when the dagger strikes an underwater object? Ian designed in a weak point into most of his board’s plans, ie they shear off at the hull line rather than rip apart the trunks from the force of the blow.

Now go back a few posts to trimaran Skateaway. Keith designed in a big wedge behind the daggerboard, sitting inside the trunk, that acts as a shock absorbing bumper. I think it’s about 5″ fore/aft at the bottom, and tapers going up. He claims that in 20 years of hard sailing in shoal areas where groundings are common, the system has worked flawlessly in protecting both the board and trunk.

Recall a couple of months ago when we reshaped our dagger, we cut 1.5″ off the trailing edge to get a better aspect ratio (more upwind lift). But I also did it to make room for a shock absorber. After a full Saturday at the boat yard, we spent an hour on the garage floor… (dang, I miss having a workshop! I wonder if Fram / Henny has that problem now too?)

That’s four layers of 12oz biax glass to form a trunk-length strip for holding the shock absorbers.

We had ordered a 6″x6″x3″ block of neoprene rubber (60 durometer) from McMaster. (Forget that 10% tolerance on the website; this thing was dead-on the advertised 3″ wide). Tablesaw literally burned rubber like an American Graffiti outtake.

These relief holes are a key part of the shock absorption. The rubber is heavy and expensive, so we compromised to this amount which will protect the board from about 2/3 deployed through fully deployed. Further up in the case the bumper is backed by wood blocks, ie what we had on hand.

It slid just right down the trunk, behind the dagger, glass side out.

The black plastic plate is affixed to the bumper, and the plate simply screwed in to the upper rim of the trunk. From the bottom looking up, you can see the lowest rubber bumper and the glass plate behind the dagger. The dagger exit slot is about 2″ too long now. We didn’t have time in this haul out to fill in the gaps. Maybe next time, for max underwater efficiency.

Don’t worry that the board looks off center in the photo. It was being forced to one side at the time.

So, to you F-boat plan holding builders out there, I challenge you: Ian’s not here to debate it with us, but why not make room for a bumper in your dagger trunk? The auto industry figured this out in the 70’s. At least we can hide ours. Make your case two inches bigger? Reshape your dagger to get a 9:1 aspect ratio. Ian designed the F36/39 board too long fore/aft for its width. Today’s foils have proved it. So perhaps fill the rest of that case with this idea!

Back when we launched Ravenswing, Charlie made an excellent CrazyCrane in the back of his pickup to help us get the floats into position on the beams. This time we needed a way to get the dagger up and down a couple dozen times for all this retrofit work. We’ll just call this one DingleDerrick. I asked the yard boss to just leave the huge crane over the boat for the weekend. But he said no, there’s no boom brake and the wind is being weird lately. So they craned up two hideous old horses on deck and pointed me to the woodpile. Got to love the DIY boat yard.

They even let me play with the gas powered pressure washer, and the boat bottom got blasted clean. The above shot has the dodger in its new top-sides matching grey. Warning here to never use the one part Interlux Brightsides paint for mixing bright colors. Our 1/2 yellow, 1/2 red Ravenswing Orange faded severely after just one summer.

Three hard days done in the yard. Labor Day is easy – applying the new graphics, running some solar panel wires, swapping the engine prop then bugging out to celebrate Dad’s 81st. Last month we finally got his boat out of her slip for a much needed shaking of the cobwebs. Selfie time…

Those smiles were a pretty good recovery from what we found upon entering the cabin that day.

I’d heard the expression “the floorboards were floating” but never really got it. Amazing what a dripping prop shaft seal and failed bilge pump can do in a few weeks unattended! Sorry Dad, I’ll stick to my three hulls / no lead setup :)

13 volts and a nice big crane

Ravenswing is up and running on lithium batteries. We came back the next morning and found all four “parallel 4 packs” had balanced out to 3.28volts. Anton caught my tired typo the whole the other night; the parallel wiring of four cells of course kept the voltage in each new 400 amp hour battery at the 3.5volt level. All 16 cells had been hand-leveled at 3.28volts about four months ago, so I was happy they had not changed at all while waiting for this week. So we then proceeded with wiring them in series, to get up to a 400amp hour, 12v battery.

13.18v is pretty low, so we hooked up an old car battery charger rated at 10amps, which struggled to get the pack up to 13.31v after a couple hours. We’re ok leaving it there until the charging sources are hooked up.

There are three serial ‘jumpers’ between the four 3.5v groups. Note the one in the middle goes through a 150amp fuse; this is the first line of defense safety for a bad short circuit situation.

The previously installed 12v distribution panel matches the digital meter, and is a good at-a-glance basic tool.

But JoeS, a Bay Area Multihull veteran ocean cruiser, wants more details! Here goes, Joe…

I’m thinking of a max charge limit of 14volts (Joe does 13.8).

Lower limit discharge voltage is still up for debate. I need to read up on my CALB cells again, and ask the supplier EV.tv for their reco.

We’re installing a CellMon to monitor the voltage of each 3.5v 4-cell grouping. I’m judging that our usage and our charge pattern will be non-stressful duty for this bank, and thus it’s not necessary to monitor all 16 cells individually. I haven’t decided about installing any battery temperature sensors.

The CellMon will signal out to a loudspeaker alarm when a high or low limit has hit. I believe a second signal can be created at another voltage value, which we can send to the battery protection cutoff to shut down the power immediately. That device is planned to be the Victron BP-100. It is Bluetooth enabled and gets programmed from a phone / iPad app.

Primary battery monitoring is a Victron BMV712. This is also Bluetooth driven by an app. We mounted it at the nav / comms desk but it isn’t wired to the battery yet. Pretty sure it handles battery temp, if so we’ll get that sensor.

All three charging sources will be brought in to a common bus setup, then routed to a smaller Victron battery protector – BP65. This will be set with a lower limit than the BP100’s master cutoff, so all charging sources will be cut off from the battery before the battery gets “too full”.

The one decision not made yet is how to control the four 100watt solar panels. I’m leaning towards four separate circuits, each using a Genasun 140 Lithium profile MPPT controller. This will be the best at dealing with shade management (because the panels are in four different places around the boat). The alternative is bringing all four solar panels into a Victron MPPT controller (150/30 model I think). I like the idea of all-Victron because their stuff works well together. But does anyone know if the single controller can do differing shade per panel management well? Arlene and Glen, have you dealt with this?

Joe, the BMV712 is lithium-programmable. You tell it your ‘tank is full’ setting (e.g. 13.8v) and it does all the math from there, providing % of capacity left, and all kinds of other info. I’m excited to have it on the boat’s iPad.

All of this battery management stuff won’t happen until after the mast build journey, so we’ll stop talking batteries for now.

Early today we motored from Richmond to San Rafael Yacht Harbor. It’s not talked about much, but perfect for us with a big crane and it’s a DIY-only yard. You can’t hire them to work on your boat, but there are contractors swarming the place. And some funky toothless guys. (And gals). The yard crew is very competent with 30-45′ boats.

They swung the boat just a few feet above some late model cars – yikes!

Farrier’s design does look pretty swanky once you can get a few steps back. I love this angle…

Labor Day Yard day 1 was all about the dagger trunk. It was much more involved than I planned, as I realized hull-builder Howard had wrapped the Kevlar keel-line protection up into the trunk about three inches, and that buildup at the very bottom of the trunk was really screwing up the dagger fit. It was arm and back burning work to reach up past the foil block and rasp & shurform & grind as needed. I also had to rip out all the shims I installed during last November’s haul out. Argh for me, and at one point I wanted to punch Howard in the face. But by 7pm tonight the board goes up and down, fits snugly and the exit slot is re-epoxied. Keen followers will remember a few months back I sliced off 1.5″ from the aft edge of the board. Next time we’ll talk about the crash bumper that’s replacing that cutout. Stay tuned.

Boom, version 2

Happy July to you. We did a bit of work on Ravenswing in June, so here’s a recap.

The daggerboard got the bottom paint for the section that rests below the standing water line.

Griffin and I took it to the boat, and darned if it didn’t get stuck in the case. It’s about a millimeter wrong, so we have a bit of shaving to do for a proper, snug fit. Nuts.

Next up is a set of upgrades to the boom. The outboard end with the turning sheaves for the outhaul and clew reefing lines didn’t do a proper job of separating and fair-leading the lines. Now it will get a proper fitted sheave box:

Under heavy sailing, we’ve had some flex in the boom’s walls, so we’re beefing up the bottom side bridges with carbon uni straps.

The reefing lines for the sail’s clew points were terminating on the boom with clutches and the winch to crank in the reefs. As Jim will tell you, that was a less than ideal set up. We’re now going to bring the mainsail reefing controls back to the cockpit. (Similar to Round Midnight’s setup, Rick). So off comes the custom pads we built a couple years back.

Back on deck, various sail handling details continue. Showing you a new cleat for the reacher sail’s furling gear to explain the new way we’re putting any holes in the deck or cabin sides. Drill oversized, swab the hole with epoxy, and bond in a bit of fiberglass tube whose inside diameter fits the part’s necessary hardware size.

Finally, a note for Arno for his fantastic new Thriller. We’re really happy with these Armstrong deck inspection hatches. They fit and seal really well. But because they don’t have any frame, they’re untethered when removed. I imagined dropping one of these at sea, and ran for the drill and a bit of string. Just a thought, Arno!

All fair now

Yea, it took a couple of months to modify the daggerboard because there really wasn’t a deadline and we worked on it only when convenient. Here’s the end of the fairing process, almost ready for primer.img_0277

and finally into Interlux Perfection paint…

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Keith, I’m quite happy with the final shape:

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Final step will be to measure for the standing waterline inside the dagger trunk, and paint the bottom 1.5′ or so of this board with the same bottom paint (Petit Trinidad) the hulls got in November.

Well since we can’t go sailing, we keep our eyes open for other water fun.  Last week Colin led us on a hike along Yosemite Creek, originating about 8 miles north of the valley. It was pretty great to experience the creek growing with every little stream tributary feeding in. img_0336

After three hours of hiking we saw the acceleration towards the falls…

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Then you get to the cliffs’ edge, and hang on tightly to the railings. We had lunch with this Raven, and I was trying to get a photo of it taking off, still working on the elusive just-right artwork of “Ravenswing” to paint on the float bows of the boat. img_0319

And over the water goes, dropping 2,400′ to the valley floor. Griffin had never seen Yosemite Valley – getting their from the top down was an amazing experience – highly recommended!

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Visiting the park during waterfall season is magical. If you’re in to water. :)

Next up on Ravenswing is touch-up painting around the new starboard side port lights (windows) – recall that repair from a few months back had to be suspended because the weather at the marina has been too cold for the LPU paint to ‘kick off’ and turn glossy.

And a big hurrah! to Arlene and Glenn for sailing their Lagoon400 cat Wahoo from the Caribbean to her new home on the Chesapeake. Sounds like they had a great 1,300 mile run northbound. Hopefully they’ll let us raft up at their swanky looking dock (nice house!!!) You can check out their adventures here:

https://wahoosailing.wordpress.com

 

Bogged down

For my son, master of word-play…

Ravenswing’s daggerboard is almost ready to paint. We’re being rather methodical and not-rushed about the fairing work. (Because the mast is still months away).

To finish shaping the board, we needed to add back the 1″ wide knife-edge taper to the trailing side. It was done in solid fiberglass on one side, a bit of thick putty in the middle, and another glass strip for the other side.

Then as the Aussies say, we coated the whole board in fairing bog. That’s epoxy mixed with the red micro balloons, mixed up like a very runny peanut butter and spread on as evenly as possible.

Also note the 4mm thick wood strips added to both sides of the portion of the board that stays in the trunk while underway. This finishes the ‘solve’ to the board having been too loose in the trunk case while sailing. (Geoff, I didn’t use plastic because this wood was sitting right in the garage and was easier to rip to the exact thickness needed)

Here’s the fairing bog after the first session with the long-board sanding paper. This nasty task brought back bad memories of the long-boarding purgatory from hull fairing a few years ago. Builders, are your arms burning yet, just reading this?

The dark spots are the too-low points, ie the sanding board isn’t hitting there to turn the red bog to the dull pink. We sanded further, looking for that fair-surface balance. You don’t want to go too far, though, and destroy the intended overall shape. getting better with a second fill and sand pass, but you can see we went too thin with the bog for a long section about 4″ in from the trailing edge.

There was another pass done after this photo, and by the weekend we should be able to show you the finished fairing work.

Update on the little 4hp Johnson: took the carb apart a second time and cleaned even deeper, but it still ran funky. Punt. It’s with Outboard Bill in Sausalito. I authorized two hours of search and rescue…

So when your wife gets you a shiny new pickup and you scrape together some dough to get it lifted up and accessorized, you DON’T expect the 4×4 shop to call with “well Mr. Carter, we had an incident on Saturday…”they got the suspension upgrade done and winch bumper mounted, then backed it into a partially rolled shop door. Geez. At the body shop now.

More reasons the daggerboard is taking too long: excellent rolling distractions. Who wouldn’t want to try out a genuine 60’s dune buggy on the Plumas County dirt track?!and while we’re in the north Sierra, hit some excellent single track on the new Hightower LT. holy cow, this bike is a bad ass! If any of you Ravenswing fans want to do some mountain biking when we’re not sailing, just holler. They’re lined up in the garage :)

Thanks Mom for road tripping to the Sierras with your kid. That was fun.

Ok, we’ll get a bunch of boat painting chores done this upcoming supposedly hot weekend. Literally watching paint dry!

Found our shape

You were probably wondering why it’s taking so long to reshape that daggerboard. Truth is, we split just after the last blog post. A great vacation trip to UT and CO. Once back home and the trailer cleaned up for the next adventure, we got out the shaping tools. Mom, the red stuff is the fairing compound applied directly to the foam core, getting the understructure shape just right before the final outer skin of fiberglass is applied.

Keith should be happy with this new foil shape. We’ve gone from a 12:1 aspect ratio to about 9:1. And remember there’s still a final 1″ knife trailing edge to add back once we get more epoxy on hand.

Next up was wrapping the whole board again with 17oz double bias glass. you’d think we’d be old hands at this by now. Got all materials prepped in advance and decided to wet out the glass on a table in the shed. Well, the combo of a fast epoxy hardener and the big cloth being folded many times to fit the tiny table led to heat build up. As I draped the wet cloth over the board the epoxy started kicking off. There was some frantic pressing in place, then realization that some had to be cut away and (thankfully there was enough) new glass cloth added. And of course, because the project is quite large, our normal “stretchalon” vac bag wasn’t quite large enough. I used 4mil basic plastic taped into a bag but that stuff just doesn’t handle as well. Only saw this on the pump and today we found some air pocket lumps on the board that mean a bit of grinding and reglassing.

Ugh, guess we’re not to be called pro yet.

Seattle Geoff stopped by today as he’s curious about current examples of upwind foils (he’s building a high performance 37′ cat now) and I was embarrassed he saw my vac bagging flub. He was kind about it :)

It’s been a few months since we finished the portabote seats and transom makeover. Today it finally got wet, using the Petaluma River launch ramp that is two miles from the house. Carlos, that thing still leaks – I need to lift it up, get some dye in the water and search for the hole in one of those seams.

The 4hp Johnson hadn’t been run in three years, including the fact that our 2016 oak tree fall had sideswiped it. Couldn’t get it started the other day so we put on the bravery pants, watched some YouTube and tore into the carb.

I cleaned out nasty old varnished gas and bad particles. But there’s still something affecting the main jet (?) because today it wouldn’t rev up beyond about 1/2 throttle. If any of you know what I should try next, please holler. This is an early 90’s OMC 2 cyl, 4hp. It’s VERY clean, acquired by a nice old man who only used it in Donner Lake.

We “ordered” the new mast six months ago now. The anxiety level about the time delay is high. Spoke to the builder on Thursday and he’s finished the ones ahead of us. Now they are doing some maintenance on the 144-head braiding machine and reloading it with the right weight carbon filament for us. It will also be used to make a boom for a J-Class boat. That’s pretty incredible sounding and somehow ironic that our main mast is the same construction as another boat’s boom! The builder won’t bother giving me a target finish date at this point – we just need to stay on top of the progress.

Alright, you’ve read this far, so maybe you’ll be mildly interested in the Carters’ western road trip. It can’t always be 100% about sailing after all. Here’s the trusty co-pilot in her pickup truck

Once into Nevada we jumped on to America’s Loneliest Highway (US 50)

Went underground in Great Basin NP at Lehman Caves

Then had the young’uns with us in Moab for their spring break. Jeanne rented us two of these

It was Jeep Safari Week in Moab

We spent a Saturday afternoon on the CO river

Met up with our Sierra Buttes Trails Stewardship team for awesome mountain biking

Jeanne found her hiking legs again and we promised each other to do more of it! Doesn’t she look great?

After Moab the SBTS team went to a conference in Telluride, which was nice but at 10,000′ on a cold morning I somehow pushed the new truck into a throttle sensor fault mode, which devolved into this on I-70 a coupe days laterthat was late on a Friday, so Grand Junction Chrysler handed us a loaner car for the weekend and we explored the beautiful area

Got more riding in at Fruita’s “lunch loops”

And the truck turned out to be a 30 minute fix on Monday for some electronics minor recall thing. A few extra days in the American West and we found various decorations to make the new trailer more homey. It’s just missing a nice framed portrait of Ravenswing in there! Maybe once the new mast is stepped…

Dagger Bagger

Sometimes it’s possible to worry too much about these projects. Last time we wrote of not knowing a reasonable technique for bulking up the daggerboard shape. After some careful measuring, it needs 5/16″ at the most, and most of the add will be 1/4″ or less.

We dug around in leftover building materials for some 1/4″ divinycel 80 (5lb density) foam core that had been saved for anymore interior panel making. Fortunately for timely efficiency (hard to get this stuff quickly) there was just enough.

The little pile of scraps was all we had left of three 4×8′ sheets from 2015.

Next we made a fresh vacuum bag with the last of the Stretchelon plastic, but it wasn’t quite big enough. So for a first, tonight we’re trying standard 4mil plastic sheeting from the hardware store. For a simple, flat part like this it’s working fine.

Thanks again to whoever dreamed up laminating curved panels under vacuum pressure. So satisfying to watch it work. This extra foam core will be very well formed on to the board.

Along with running out of vac bag film, we’re out of the fabric breather that lets air flow inside the bag, and soaks up excess resin. A quick web search at lunch today turned up an airplane builder who uses paper towels! He said use four+ layers. It was soooooo much easier to keep in position tonight, and nearly free. We’ll let you know next time how it worked.

In that last shot notice the darker seams in between the pieces of tan foam. That’s epoxy being forced up, and that will make the shaping process more difficult. The tools need to move between the hard glue lines and softer foam without gouging. There’s the downside of using all the scraps instead of single full sheets. We’ll just have to be careful.