Follow This Project On Facebook

Lately I have just not had time to post updates to this blog. I do post activity on this project more frequently on Facebook. If you are interested in whats happening, I encourage you to click 'Like' on the Facebook badge below. Or go to http://www.facebook.com/westsail42/

Posts to this blog will happen infrequently, if at all. The blog will remain accessible for historical purposes.


Sunday, October 18, 2009

Anchor Roller Test Lab: Preliminary Results

From Building A Westsail 42: Latest Activity
Yesterday I setup the apparatus intended to help design various anchor roller configurations for different style anchors. The goal is to get a design that self launches, easily retrieves various style anchors. The idea is to design the "cheek" plates to allow placement of the rubber-like rollers in different places for different anchors.

The apparatus is simply an existing work table with two pieces of plywood simulating the cheek plate, approximately the size expected and then some (so I could cut them down and really dial it in). Two rollers are mounted between the cheek plates using two pieces of all-thread as an axle, through holes strategically drilled through the plates. Also included is a 15 foot section of 3/8" chain and a standard shackle to test deploy and retrieval of the anchors to help simulate a real world setup.

I started with the bow roller placement from the initial CAD drawings done a couple weeks ago. This initial setup worked pretty well for all anchors I had on hand (Bruce, CQR, Delta). But the Bruce and CQR had trouble self-launching. Moving the aft roller up about an inch fixed this. Finally, I jacked up the front of the table to an incline I expect the pulpit to be at in order to match the sheer of the boat. It is about a 6 degree incline. Again the Bruce and CQR had trouble self launching, so, the aft roller goes up another inch to fix this.

In the end there are a series of holes in the cheek plates with pairs matching the optimal position for each style anchor.

Testing is not done however. I will be exchanging the 44lb Bruce for the 66lb this week to see if there is any significant difference for roller placement.

As for the "rollbar" style anchors like the Rocna, the problem is the rollbar hitting the underside of the pulpit as it is pulled in. The easiest solution is to drop the forward roller a couple inches. However, we cannot build that extra drop length into the cheek plates as it will screw up the optimal setup for the other anchors (like the Delta and CQR). Specifically, the cheek plates will hit the flutes of the anchor and block it from being retrieved into the fully stowed position. So, I am considering a couple removable "tangs" that will attach to the cheek plates and drop the forward roller. If we use a Rocna style anchor, we add these tangs and drop the forward roller. If we go back to another style, we remove the tangs and move the roller back up. That is the idea at least. Clear as mud? I will probably have a CAD drawing here shortly to clarify things.

From Building A Westsail 42: Latest Activity

12 comments:

The Incredible Hull said...

Great stuff. Looking forward to following developments. Hopefully you will be snowed in soon as I have a bunch of projects for you to work on this winter.

Greetings from a chilly Miami, we are expecting 59F tonight and trying to remember where we stored the blankets last year.

Gerry

Colin&Lizzy said...

The problem is that the test is static and the bow never is. I guess you can only go so far with that. One thing I have always wondered about is changing the tackle so that there is a heavy swivel attached to the anchor followed by, say 18 inches of 7/8"
SS round stock, another heavy swivel and then the chain would start. This would reduce the amount that the anchor swings once the Stainless shafting starts over the sheave or wheel at the end of the roller ass'by. It is just a thought exercise but I think it would improve launch and retrieval.

rj said...

Colin, interesting idea. Yeah, this is not exactly a pitching bow. Furthermore, there is no guarantee the boat will sit on her lines when launched. Could be a little bow up or bow down (likely bow up). Just in case I will be drilling another rear roller position one inch higher if needed to help with the self launch.

Gerry, don't freeze down there. Oddly enough, just after a very mild indian summer here in the PNW, we hit record lows one clear night last week.

The Incredible Hull said...

Hi Colin

I agree that it is an interesting idea. However, I have a a love/hate relationship with SS swivels, mostly hate. Two of them with a SS bar would definitely offend my KISS principles. Still, I remain to be convinced.

Colin&Lizzy said...

I think I might mess around with the Idea. I get that the big Westsail is a heavy boat but the bow is always the most active place on the boat in terms of rolling and pitching. I have seen some comical solutions to keeping the anchor clear of the fiberglass when dangling.(The sailboat as a sailfish)
The idea behind the SS rod is to keep the weldment from getting too long. The rod would act like a fulcrum which would force the anchor away from the hull as it is drawn over the roller. It would raise a few eyebrows. I see your point about the two swivels. I would have to machine something robust up. Winters coming, play time on the Mazak, not much else to do right now!

The Incredible Hull said...

Rj

Off the subject but what was the thickness of your fuel tanks.

Gerry

rj said...

Gerry, fuel tanks are 1/8-inch T-5052 aluminum.

FWIW (since I am looking at the invoice), water tanks are 14ga 304 stainless.

The Incredible Hull said...

RJ

Thanks for that info. As I know you gave the matter some thought why did you go for .125 and not .25 thickness for the aluminum tanks?

Gerry

rj said...

Gerry,

.125" Was what the fabricator (http://coastline-tanks.com/) recommended for the tank sizes. Each big tanks has two baffles welded inside which help give structural strength. I trusted the guy as he is the sole fabricator for a local production builder (Nordic Tug).

.250" strikes me as quite thick for tanks this small, but it would work.

Jerr Dunlap said...

I let my anchors out so they'll self-launch when the time's right, as I'm preparing to anchor. Really, I wouldn't worry too much about self-launching because if the weather's nasty enough to really not be on the bow, you're probably not going to be able to anchor and should be out to sea. You're doing the right thing with your mock-up!
On another note, that's not the "Bruce" Asian knock-off, is it? If so, return it as fast as you can - West Marine had so many returns of them (I saw several) they stopped carrying them. The shank breaks off from the blade due to very poor metal and casting.
Yes, .125 is just right - Very strong and half the weight.
- Jerr
ps - I'd be interested in your thoughts on my anchoring series of articles, Gerry, Collin and RJ - I'm planning on publishing after New Year's.

rj said...

Jerr,

It is the SeaDog-line knockoff. I am sure it is asian made, but not sure if it is the same one WM oem'd.

Sure, look forward to your anchoring articles.

I added your blog to my list.

Jerr Dunlap said...

Thanks RJ - I'm looking forward to any input you may have. Best wishes with your Bruce - It's a terrific design and I'm glad to see you're aware of the need for different anchor types. You've got a terrific blog and I'm quite impressed with your thoughtful, sound design and construction.
- Jerr