Backstay Chainplate

This project has been in the works since February, but it didn't all come together until this past weekend. It's part of the 'Get the decks waterproofed before I take the cover off project', but the backstay chainplate also falls in the project 'Make the rig strong' category.

I could have saved myself a lot of work by just bolting the old chainplate back in and calling it a day, but I had a few concerns about the strength of the almost 40 year old aluminum chainplate.  Unlike the stainless steel that makes up the shrouds and forestay chainplates, the fatigue strength of aluminum tends to decrease steadily with the number of stress cycles, and can fail with no warning signs.  Since the backstay is pretty critical to a boat's rig, I figured it was time to get a new chainplate made up.

I also found some water intrusion problems when inspecting the underdeck knee where the chainplate mounts.  The chainplate has four bolts that connect it to the knee and all of these holes clearly had some water damage and needed to be fixed.  Unfortunately, access to the knee is not great and requires getting into the lazarette and wriggling aft around the propane box to access.  I decided on a 2 step approach to rectify the problem.  

The first step was to overdrill all the existing chainplate holes (back to unsaturated wood), then fill the holes with structural epoxy and retapp.  The original bolts were 3/8" so I overdrilled with a 3/4" bit and found that there was no water ingress beyond that (phew).  I taped the backside of the holes and saturated the surrounding wood with unthickened epoxy.  Once that kicked, I filled the holes with thickened structural epoxy and used a small trowel to smooth out the side that was not taped.  

While all this was happening, I redesigned the chainplate in CAD so the new chainplate would have additional area that would connect further down the knee. Probably overkill given that the first one lasted almost 40 years, but it certainly wouldn't hurt to have additional connection points in the 'meat' of the knee.  I went through several iterations and 3d prints of the design to test fit before I sent the final version for machining.  

I contacted Mike Quill (the rigging foreman for Niagara when the boat was built) Mike Quill Yacht Rigging and as always, he got back to me very quickly and informed me that the original backstay chainplates were made of 6061-T6 with a hard anodized coating.  So I went with the same material and sent the design off to the machine shop (Xometry).  Three weeks later the shiny new part was in my hands and ready to install (cost was ~$210 shipped).

Once I had the new chainstay, I retapped the 4 holes that the original chainplate used and dry fitted the new chainplate.  Then I tapped the additional 5 holes to secure the new chainplate along the lower section of the knee.  I sanded everything down and then re-painted with epoxy bilge paint before bolting it all back together.  I had to enlist the help of my wife to get a wrench on the backing nuts while I tightened the bolts down with a socket.  I'm not sure how happy she was getting stuffed into the lazarette to perform extreme boat yoga, but she didn't complain.  

With the chainplate secured, I moved up on deck to seal off the opening.  I 3d printed a TPU (D95A) sleeve to go around the chainplate opening and then put down strips of butyl tape on top before screwing down the chainplate cover to compress the butyl tape and make a watertight seal.  Probably a lot of work and expense, but I won't be worrying about the backstay breaking loose on my watch.

One Thing Leads to Another

Despite my best efforts to get the decks waterproofed so that I can remove the cover, the past month has been way too cold to do much caulking so I turned to what I thought was a simple project that I could knock off in an afternoon.  The original shorepower inlet plug was pretty old and I could see cracking on the rubber gasket where it seats on the deck so if exposed to weather it would probably leak.  Since I had a brand new one in the shop, I figured I'd just replace it now because it didn't need caulking to waterproof it.

Of course, as with all things boat related simple things just seem to take way longer than expected especially when I'm working with 1-3 hour blocks of time that I can carve out.  You'd think I would learn after all these years working on boats. Nope.

Replacing the plug was super easy, I just had to pull the old one off, disconnect the 3 AC wires that fee the AC panel and reconnect them to the new one. Since the new plug was a direct replacement of the old, I just had to plunk it back in place and bolt it on.  While I was replacing that though, I remembered that I had a brand new galvanic isolator that came with the boat and even though I rarely (if ever) plug into shore power, I figured I might as well install it while I was in there.  Since it was still too cold to do any caulking so I decided to tackle that.

A galvanic isolator is essentially a box with several diodes in it that blocks stray DC current on the AC safety ground when connected to shore power.  I don't fully understand the galvanic corrosion process, but I am all for reducing the possibility of corrosion on exposed underwater metals (shaft, prop, strut, etc...) and these devices are apparently helpful in preventing this.  Plus, I had a new one in my shop (ProMariner ProSafeFS 30Amp).  

Installation was straightforward and the hardest part was finding a good location between the shore power inlet and the AC panel and mounting the device in the fairly cramped lazarette.  Wiring it only required cutting the AC cable and running the safety ground (green wire) through the isolator.  I used a waterproof junction box to connect the wires coming from the shorepower inlet to a new AC cable (3 wire 10awg) that goes to the AC panel.  The old cable had some signs of chafing and figured it would be best to replace it while I was in there.

From there I spent a few hours bundling and securing the new wire in a run that terminates at the AC panel. This run goes from the galvanic isolator to a bulkhead and through the top of the engine compartment to the panel.  I was really thankful that the engine is not installed yet or it would have been next to impossible to get it bundled, tidy, and well secured.

At this point I was fully immersed in the AC system and decided to just plow through and replace the old AC main panel with a new Blue Sea Systems double pole breaker panel (#8027).  This would have been a straightforward job of just swapping out the old panel with the new if I hadn't decided to install the new ProMariner TruePower 1000w inverter to power the AC outlets with the battery when not connected to shorepower.  

There are many ways to install an inverter in a boat and the easiest way is to install it inline between the shorepower and AC panel. However, if installed this way then when inverter is connected to the house batteries, it could potentially power all the AC circuits on the boat, including the battery charger.  I'm not an electrical engineer, but I do know that you can't use battery power to run a charger to charge the battery.  This would fall into the perpetual machine world and physics tells us that it isn't possible.  

With this in mind, I decided to take another approach: install the inverter on a branch circuit that only powers the AC outlets.  This is a common installation method as well, but because the AC outlets on Velorum were originally wired as 2 circuits (port and starboard), I decided to combine them into a single circuit downstream of the inverter.  

The schematic below probably explains the AC portion of the installation circuit better than I can, but generally speaking the flow goes as follows:

1. AC Shorepower -> Main Panel
2. Main Panel circuit breaker -> Inverter
3. Inverter -> Junction box that combines port and starboard outlets

For the installation, I built a shelf in a compartment underneath the quarter berth next to the battery compartment and ran the AC cable from the panel along with positive and negative 2awg battery cables from the battery bank.  All of these connect to the inverter and depending on the power source, it sends AC power out of the compartment to a waterproof junction box mounted in the engine compartment and combines the port and starboard outlet circuits.

All in this took about 2 weeks of replacing the AC panel, running cable, building a shelf, securing cables, and connecting the junction box before it all came together.  A lot of work that all started because I decided to replace the shorepower inlet plug!

AC Schematic

Inverter Battery Disconnect and Monitor

New Main AC Panel (almost installed)

Inverter Installed 

Junction Box Combining Port and Starboard Outlets

Hatches, Ports, Handrails, and Refinishing Dorade

As part of my effort to get the top of the boat waterproof so I can remove the cover for the engine install, I started knocking items off the list that I posted last week.  We had some warmish temps over the past few days so I was able to get all the opening hatches (5) and opening ports (6) regasketed.  The hardest part of the job was getting the old gasket and sealant out (see last post for details).  

Once the hatches and ports were prepped, installing the new gaskets was actually pleasant.  Just cut the correct gasket based on the perimeter of the hatch channel, lay in a bead of Silaprene and press the gasket in place.  Once it's seated, just close the hatch and clamp it down.  24 hours later the Silaprene had cured and the gaskets were locked in place.  Easy peazy and the Silaprene was nice to work with.

Moving on to other holes in the deck, Steph and I tackled the handrails.  I had removed the handrails last fall and brought them home over the winter to clean up and re-varnish (12 coats) before re-installing.  Originally, I had big plans to change the way they were affixed to the deck, but never got around to it.  The handrails as designed were screwed in from the underside of the deck with 2 woodscrews in each mounting point.  Hinterhoeller did do a nice job providing holes in the headliner to access each screw, but the rails really should have been through bolted for a number of reasons.  The original design team incorporated a lot of well thought out ideas for the Niagaras, but using wood screws for handrails was not one of them.

• Through bolting provides a much stronger connection than wood screws.
• Allows easier mounting of the rails since the longer handrails are curved and need to be bent into place.  
• Gives more sealant options. I'm a big fan of butyl tape for sealing through bolted connections, but you can't provide enough compression force for butyl tape with wood screws

Anyway, I settled on using the woodscrews again and it was a bit of a bear to get done.  Starting at the aft end, we mounted the smaller handrails (4 mount points) without too much issue because they were straight and didn't have to be bent in place.  We taped off the area around the rails and I laid down a bed of 3M 4200 sealant on the rail and then set it in place.  Steph was on deck holding the rail in position while I screwed up from the bottom, gradually tightening each one.  The larger handrails (7 mount points) were much trickier because Steph had to hold the rail in place until I got the first 2 mounts screwed in.  Then she carefully bent the rail inward and I moved to the next one.  The hard part was keeping the next few mounting points off the deck so the sealant didn't smear everywhere.  We managed, but I can't say that it was my best job.  They are solid and should be watertight, but the sealant looks a little janky in spots.

Handrails installed

Like the handrails, I brought the dorade vent home to clean up and varnish over the winter.  When I removed it last fall, it was screwed directly to the deck and appeared to be penetrating the cabintop core.  When it came time to reinstall, I overdrilled the holes and filled them with slightly thickened epoxy and let it cure.  Once cured, I re-tapped the holes so there would be no water intrusion into the core going forward.  Tapping around the 4 mounting points didn't reveal any core issues and when I overdrilled the holes, the wood chips coming out were dry, so I think I caught it before it became a problem.   

Reinstalling was just a matter of applying sealant where the screws penetrate and screwing the box back into place.  Then I sealed the lexan cover with silicone (clear) and screwed that down along with the new cowl.  

 

Back to Work

We had a pretty cold winter in NH that kept me off the boat for a few months other than to check in to make sure the cover was holding up. However, the planning and scheming never stopped in my head and did do a few minor projects over the past few months.  The planning I did was really a logistics exercise for the engine installation and I found a surprisingly large number of things that need to be done before the engine actually gets hoisted into place.  Additionally, some of the items on the list are temperature dependent and have to be done once the temps start to rise.

So in a nutshell here is what has to be done (in rough order):

• Waterproof the top of the boat (The cover has to come off during engine install)
• Replace all gaskets on hatches and ports
• Rebed fixed windows 
• Rebed deck hardware 
• Finish installing and bedding chainplates
• Cover engine control cutout
• Cover instrument cutouts 
• Prepare engine compartment (temp dependent)
• Assess engine beds
• Add additional glass if needed
• Paint compartment
• Re-install strut (maybe temporarily to aid in shaft alignment later)
• Clean up and re-install exhaust and bilge pump fittings on stern
• Re-install water lift muffler and exhaust pipe to transom
• Choreograph engine installation plan
• Once the engine is lowered into companionway, how to get it onto engine beds
• Installation
• Remove cover
• Remove framing so crane can lower engine
• Schedule crane (the farm where I keep the boat has a myriad of big machinery, but I need to coordinate with the owner)
• Measure companionway opening and determine what needs to be removed from engine for install
• Run engine at shop and drain coolant (oil too?)
• Move engine from shop to boat and prep for hoist
• Hoist engine into boat
• Get engine on beds.

There's a lot of little things that won't take long and I know what to do, but there are a bunch of unknowns that I haven't done before and they are going to take some thought to do it right.  Of course, after this is all done, I'll have to re-install the transmission, get the shaft aligned and installed, and install the new engine control panel, but I'll tackle that when I get there.  

Now that I'm seeing some cracks in winter's grip, I've started on the waterproofing step by removing all the hatches and bringing them home to replace the gaskets.  Most of the hatch gaskets are pretty old and cracked so I ordered 3/8" and 1/2" round neoprene gasket material (Trim-LOK rubber cord seal) to replace what was there.  Removing the gaskets is tedious and slow, but not difficult.  The gaskets themselves come right out, but the sealant (Silaprene) is tenacious and I found that the best technique is to use a rounded wood cutting gouge and get under the sealant then slowly pull it up as you work your way along around the hatch.

It's still a little too cold to re-apply the gaskets. Silaprene requires 40 degree temps and right now we are in the 30's.  Once we get a few warm days in a row, I'll re-install all the hatches, apply new sealant, seat the gaskets and then close them up (that will give even pressure to the gasket on the hatch so it can seat and cure properly).  I haven't tackled the 4 opening ports yet, but that's on the list for this week.

In other news unrelated to the engine install, I revarnished the cabin sole section at the base of the companionway steps.  The existing varnish had peeled up in the corners and it just looked ugly.  I brought the section of cabin sole home and using a heat gun, stripped all the old varnish off and then gave it a quick sand with 220 grit to get any remaining varnish off.  I followed up with 12 coats of varnish.  I think it looks pretty good, and I'm hoping it won't make the rest of the cabin sole look shabby.  The other sections look good to me, but once installed I'll know if the others will need to be done as well.  

Finally, I don't like the exposed location of the engine controls, they are in direct sun and initially I was going to build an inset for the controls that would keep them somewhat protected when not in use, but I ended up designing a cover (AutoDesk Inventor) that I could snap on when not in use (most of the time).  As we speak I'm printing the prototype on my 3d printer using  TPU filament (95A durometer).  TPU is a flexible filament (like rubber) and should be a decent solution.  Time will tell how long the TPU will hold up in the sun, but even if it lasts a summer, I can alway print another.