Building a spinnaker crane

[sailah]

Let me first say I'm not a professional or an engineer. Or a welder.

But that doesn't mean I don't like to pretend I am.

I decided to add an asymmetrical spinnaker this year and my uncle, who used to be an engineer at Schaefer told me I needed a spinnaker crane. I looked at the available options and decided to design my own. It's going on my Dickerson 37.

Here's what my masthead looks like. I removed the strut that has the windex and antenna for now. I'll have to cut that and reinstall in sections drilling and tapping into the crane.



Drew up the part a few times in Autodesk Inventor until I was happy with the part and strength. I modeled a 3000# point load on the end of the bail and the deflection was acceptable. Printed it out on card stock and checked it a few times.

I sent the files to be laser cut from 316 stainless by a shop in MI, I think they did a great job, everything fit together perfectly out of the box. I need to add bevels to the ends of where everything fits together and weld it up. I bent some 3/8" 316 rod for the bails.

This was the first version I had done and it was too big so I'm having it redone to my final draft.





I have a bunch of other stainless parts i made for the spinnaker install that I have already welded up. Once I finish the welding on the crane and drill/tap the holes I'm going to passivate the stainless.

It ended up being a little heavier than I wanted but it surely won't break.

[TheOffice]

Nicely done! I had my rigger buy 1.5 inch stainless U channel for a crane on my 44. We'll see how it handles the load.

[Suijin]

Well it's definitely going to be strong enough, lol. Don't forget to post pics of the complete install.

[PhiSig1071]

You wouldn't happen to be the same "sailah" that is on ADV? That built an Adventure FZ1 and 650 Ninja? If so this is going to be a great build.

[sailah]

Originally Posted by PhiSig1071

You wouldn't happen to be the same "sailah" that is on ADV? That built an Adventure FZ1 and 650 Ninja? If so this is going to be a great build.

The same good to see you on this forum

Still got the bikes, not much riding these days

[sailah]

Got some good welding time in tonight. Stainless pulls wicked when welded I've noticed much more than carbon steel. So I tried to keep things well clamped on a strongback and also to minimize welding.

I ended up cutting about 5" off the end and will need to shorten up the uprights. But I didn't have time to wait in getting new parts made, this project needs Tom get wrapped up soon.

Welded the X first then clamped things down to weld everything else.



I cut some drain holes with the mill so the crane could shake any water loose.



Made a simple bender to bend the 3/8" 316 bails, was pretty easy with a long lever arm



Now I need to test fit on the mast and mark where the bolts will be.

[Valmika]

What shop did you use for the cutting? I have a few projects of my own ;-)

[sailah]

I have now used 2 laser shops for this project.

For the bowsprit parts, I used a company in PA called Diversified Cutting Solutions. They did a nice job and were very reasonable on the first project. Including the 1/2" 316 plate they charged me $75 total.

This is the part they did. I made the part with bolt holes they made the "jaw" with the curvy parts as well as the part that mounts to the stem to receive the bobstay. Basically the 1/2" parts with mill finish on the left.



After welding and some scotchbrite time



Then I needed the spinnaker crane done from 1/4" plate. I had reached out to another shop in MI and they were comparable in pricing to DCS. When DCS somehow wasn't responding to my requests for a quote I inquired with the other shop called Precision Wire EDM Service. They cut all the parts for the crane, including the plate for $125. And they were lightning fast. I think they shipped out the next day on my UPS account. DCS actually just emailed me apologizing for the computer problems and quoted $300 for what Precision Wire did for $125.

I buy lots of stainless and brass rod stock at work (like by the ton, comes on a flatbed) so I can certainly get material cheaper than most. But to buy the material just doesn't make sense for me and have it sent. So if you have projects you want cut ask them to include the material or get it for you they probably have lots of drops from other cutting projects they can use.

I have a lot of experience with waterjets so I just assumed these parts would be faster on waterjet vs laser but I was wrong. The cut quality, even on 1/2" plate was way better than I expected. The parts warp slightly but I'm talking a tiny amount that a dead blow can straighten out.

I provided all cut files as DXF to both shops.

So having used both shops I'd say Precision Wire EDM is my go to for this. Ask for Kim she's who handled everything for me.

Plastic & Metals Cutting | Fabrication | Pittsburgh | Waterjet, Laser & Plasma‎
Precision Wire EDM - Wire EDM, Cryogenic Tempering, Water Jet & Laser Cutting

[Dave22q]

my Morgan was slightly more complicated because the mast head slopes down about 20 deg so my rigger used a 4" stainless u channel (1/4 stock) and welded a 3/8 u- bolt to the top. channel sides cut for level top, rig secured by 4 bolts thru the top into the masthead.
For a level masthead could be a simple plate with u bolt welded on top. Heavy ss u-bolts sold cheep as bow inserts.

[AndyEss]

Your welding work and engineering looks excellent.
Well done!
Thanks for the links to the EDM shop

[UNCIVILIZED]

Note that generally the further you get away from the water, the cheaper the prices on things like these. Since anythiing run, or owned by the local "waterfront mafia" is going to cost significantly more. Just like anything with the wore "marine" in it's title.

Obviously you want to work with a reputable firm, but it's a lot easier to shop around for fabrication shops than it used to be. And it's definietly worth taking advantage of, especially if you'll be in the same town as the fab shop for whatever reason, while your part(s) being made.

But the cost difference thing even applies to having holes drilled in stainless. And there are plenty of industries who's quality of work equals or exceeds that of maritime vendors. If for no other reason than boat gear is "botique" style equipment. Whereas with stuff for construction, farming, & other commercial app's isn't, necessarily speaking. And guys who fabricate things for tractors aren't going to have the same kind of overhead as will a shop withing walking distance of your boat.

Though with the latter, it's easy (& common) for the guys making boat gear, to walk down to your boat with the half finished part, & determine if it'll fit, as well as do the job optimally. Which ain't the case with a fab shop in Wyoming. And this is where your having made high quality, detailed drawings really pays off. Knock on wood.

[sailah]

At the advice of my Uncle I sent the parts I had made to be electropolished. I tried to make them look as good as I could with my scotchbrite wheel beforehand.

Anyways they came back and look fantastic. Very pleased with the results. The cost was $175 but I avoided having to passivate the parts myself for corrosion resistance. And they look so shiny!!









All that is left is to bed and bolt them on.