Updated on October 13th, 2020
The chainplates on our Alberg 30 were original. They were covered in 55 years of paint and sealant and were leaking like crazy. They were also starting to show enough signs of wear that it was making us uncomfortable. Since we are getting all new standing rigging this year we decided it was also a good idea to replace the chainplates.
Fabricating your own chainplates can be a bit of a pain but worth it when you look at the cost of paying someone to make them versus doing it yourself. To have a shop make them for you and you are probably looking at $100 per plate. Andy made all seven chainplates for about $120.
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Chainplate Materials
- 316 L Stainless Steel 1 ¼”x ¼”x74”
- Tap Magic or WD-40–Tap Magic is preferred but if you have WD-40 hanging around it’ll do.
- Cut Off Wheel
- Drill Bits
- 80 Grit Flap Wheel
- 320 Sand Paper
Chainplate Fabrication Tools
- Angle Grinder
- Drill Press with Low-Speed Setting–You could potentially use a high power drill but it will be very difficult. Try borrowing one, or look to see if you have a maker space in your area. It’ll be cheaper than buying one, unless you plan to use it all the time. If you’re super fancy and you have a bridgeport…can we be friends?
- Countersink Tool
- Transfer Punch
- Bench Vise
Safety Tips for Making Chainplates
- Be sure to wear protective gear when using the angle grinder. A welding jacket, safety glasses, and heavy gloves are necessities. A full mask is even better. Don’t forget about ear protection!
- Be sure you are grinding and cutting in a well-ventilated area.
Removing Your Existing Chainplates
When you remove your existing chainplates from your boat, you will want to make sure to mark each one with its location. There is a chance (especially with the older boats) that they are all different lengths (even from port to starboard) and you’ll want to keep to your original lengths especially if you are not replacing your rigging at the same time.
Measuring Existing Chainplates
The first step in this process is to measure your existing chainplates. You’ll want to get measurements for the following:
- Length
- Thickness
- Pin Sizes
- Bolt Hole Sizes
Once you have measurements you can decide if you want to stick to the original design or if you might want to beef up your new chainplates. It is worth a little research to find out if the chainplates are a weak point on your model of boat.
On our boat, an Alberg 30, the bolts are notoriously undersized so we upgraded to 3/8″ from 1/4″. We also made the chainplates themselves slightly thicker from 3/16″ to 1/4″. This was mostly due to cost and availability but we also don’t hate the extra strength.
Trace and Cut to Length
You’ll want to trace your existing chainplates onto your new piece of steel with a little space in between each for the grinder. This is just a rough tracing to get a starting point, but make sure you mark each one with its corresponding location.
Using the cut off wheel on your angle grinder cut each piece you have traced. Cut them slightly oversized but not by much because you’ll have to grind off the extra.
Once you have the rough cuts, you will want to do a more detailed tracing of the end radius and mark the holes with a permanent marker. You will also want to use a transfer punch tool to mark the exact location of the holes, so you have a starting point when you begin drilling.
Cutting and Grinding the End Radiuses
Andy used the cut-off wheel to finish removing the bulk of the material. Mostly he did this on the two corners and the top. Once there was less material he used the flap wheel to get it much closer to the original curve. He still left it slightly big because he is going to match it to the existing chainplates in a later step.
Drilling Holes
When drilling holes in stainless steel it is important to go slowly and keep things cool. If you go too fast or things get too hot you will work harden the steel and make it too hard to drill. This will mean you have to start over. Booooo!
Because our drill press isn’t powerful enough to drill to the size we needed in one step, we needed to “step it up” and started with 1/4″, moving to 3/8″ and then 1/2″ for the pin holes. You may find if you have a cheaper drill press, cough Harbor Freight cough, you may have to use this same technique. It takes longer but if you try to do it all in one step you will likely harden the steel beyond workability.
Andy used WD-40 as his coolant while drilling so this required stopping frequently to spray. We recommend if you have it available to use Tap Magic as it will not require as many reapplications.
When drilling be sure to use lots of pressure, and to pull back occasionally to “cut the chip”. You don’t want long chips, they will start to get wrapped around your bit. The pauses also help keep the bit cool. In machine shops, they call this “peck drilling”. Fun engineering fact: many CNC machines have peck drilling built into their software (G83).
Chamfering the Holes
Chamfer the holes using a countersink tool just enough to break the sharp edge and remove burrs. Do not overdo it! Going too deep will reduce the area where the pin touches the plate and could cause it to deform and fail.
Matching Radiuses to the Existing Plates
Andy bolted the old chainplate to the new chainplate through the freshly drilled holes and then ground down the new chainplate until it matched the old chainplate. I quote “it’s not an exact science”, but don’t go overboard. Go slow and check your progress regularly. Also, be sure to hold the grinder perpendicular to your work.
Make ‘Em Shine
Everyone knows this is the most important step. Well, at least if you ask most sailboat forums. It’s not actually as important as everyone makes it out to be but it is important to sand away any big groves.
First, Andy went over all edges with the flap wheel to remove the mill scale and any burrs. Then, he came back with his orbital sander and 320 grit paper to remove any scratches left from the 80 grit flap wheel. This left a brushed stainless look. If you want your’s to really shine, you’ll want to follow up with 600 and 1000 grit.
If you don’t want to do all the sanding, you can send your new chainplates out to be electropolished but this will increase your costs.
woot!