Windpilot Installation Chap. 2 – Vigor

[Bob Schwartz]

John:

Since I received your email, I did my own set of measurements and I am in agreement with you about the problem. Let me review what I did, the conclusions that I drew, my plan, etc. (wish I could send pictures)

I cut a piece of plywood in the shape of a U with insides sloped in. The tip of the “tines” matched the outside edge of the supplied washer if 8.5” spacing of centers was drilled. By slipping this device where it snugged up to the thing, I established the maximum height at which two holes drilled straight out 8.5” spacing, could be drilled. (new to this exchange? Thing or “box” defined below)

I used this as a starting point. (curvature discussed later) I then, using a level and tape measure, measured to lazarette top, added height to hatch top to get bolt level to hatch top. I used a laser level and tape to measure hatch level to deck level and the calculated vertical height to bolt level on the outside. The measurements are summarized below

Height top mounting bolt to top edge lazarette (inside) 6
Additional height of Hatch 15/16
Ht top mounting bolt to top of hatch 6 15/16
Less difference elevation hatch top to top of wood at stern -1 9/16
Vertical distance from top of stern to level of drill holes 5 6/16

I built a temporary stand in my back yard and mounted the Windpilot to it. I slanted the mounting surface 27 degrees, which I calculate to be the rake of the stern. The top of the T bar (which was supplied) is just under 5 inches above the level of the top bolt height. So, the top of the the T bar is about a half inch below deck level. Ring 345 is about an inch or so above the T bar in the vertical position. I do not see a problem with steering lines at this level.

I did not find a 4.5” recommendation of which you spoke. I am curious where this came from and how it is measured. (from what level, vertical or length along transom?)

Instruction 1.4.1 lists 5 criteria (which are actually 2 mounting instructions and 3 criteria) Two criteria relate to transom clearance. My backyard mounting project showed this to not be a problem. The last criteria is that the height of the 435 mounting bolt on the rudder blade should be 4-8 inches above the water line. The instructions are ambiguous in this regard. 1.4.1-1 says 4-8 inches. 1.5.1 says 2-4 inches. My measurements were not quite a precise, but I calculate that the top of the deck to bolt 435 is about 26 inches. I measure the top of the deck to the water line to be 31 inches. That puts the bolt 435 level at 5 inches (correct by 1.4.1-1 but high by 1.5.1)

So far, so good, until we get into this messy issue of curvature of the stern which you correctly identified as an issue. I looked over the edge, and the curve of the wooden deck at the stern seemed to match the curve of the stern. I traced the line of the deck to a piece of paper. The geometry gets a little hairy here, but what I did gives a good approximation of the added distances caused by the curve. At 8.5 inches straight distance across the curve, I stuck tangential lines and with a protractor drew lines perpendicular to the tangent. The rounded mounting post (part 860) is 2 inches deep. I measured 2 inches out the tangential lines and measured across. The curve widens this distance by 5/16 (i.e. 8 13/16). This does not include the narrowing of the lines (bolt centers) on the inside of the boat. However, I cannot estimate this without some estimation of transom thickness.

Bottom line – we both agree, this will not work, without some modifications, because of the thing & stern curvature.

I emailed Peter. I told him that I would spare him the details (which I have not spared here) but, my calculations show that 8.5” would be minimally acceptable spacing except for the stern curvature. I further told him that another CD 27 owner was in the process of installation and had reached the same conclusion. I posed 3 questions: 1) would it be OK to put washers between 810 and 825 to increase the width about ½ inch?, 2) what is a good estimation of transom thickness?, and 3) “There is a triangular area around the box where the fiberglass is thicker – about ¾” beyond the box. I presume this is to support the stay. Is this the area in which the bolts should be drilled?”

I got a response from Peter today. Question 1 – emphatic NO. Question 2 – no answer. Question - 3 “I would simply drill the MF1 in an appropriate height and see afterwards at which position inside the lazarette the fiberglass should be machined a bit away. I would not fear to machine some of the material away since this boat has been built very strong. Just compare: todays boats (list of 3) are having fiberglass thickness at the transom of about 4 mm only … and even these boats are lasting”

I told Peter, in my email, that I was not complaining, that I was impressed with the unit and have great appreciation for the complexities of installing the windvane on many different boats. Our correspondence has been quite cordial.

I am going to ask Peter what he thinks about beveling 860 to match the transom curvature and going straight thru the hull. A beveled spacer would also work. I will probably copy Peter with the above analysis.

Before I make my move, I want to re-measure everything, at least once. I think I will try to make a wooden jig to guide the drill bit thru the hull at the precise angle; and I am inclined to try to drill at least the first, and maybe both holes from the inside. A quarter of an inch off on the interior could cause some major grief, and even with the most precise measurements, going from the outside seems a bit like a crap-shoot.

John: I write this for your edification. I am interested in what conclusions you have drawn about installation height. Lets use center of top bolt as a reference point and top of deck at stern as other reference point. Please advise if your measures are vertical, or angled distance along the transom. Also, please advise if you think I am missing the boat (pun?) in my analysis of the above. My objective is a good installation with minimum modifications to my boat and Peter’s creation.

Others: If you are still awake by now, a miracle has occurred. The box or “thing” to which we refer, is a trapezoidal shaped boxlike structure that is wide at the top, narrow at the bottom, the front edge of which is about vertical. It is directly in the centerline of the transom and attached to the bottom of the deck at the top. We speculate that it may have something to do with shroud support. If anyone has any general insights as to this challenge, please advise. I am particularly interested in how thick the transom may be at that point and any insights as to the box (proper name, function, effect of carving into it, etc.)

Thanks all,

Bob

CD 27

[John Vigor]

Well Bob, you are overwheming me with science here. I'm afraid my approach is governed more by Rube Goldberg than by Einstein. I was just going to bolt the darned thing on and fiddle around until I got it right. Chop off a bit here, add on a bit there, sort of thing. The same way I cook.

I hate to admit this, but I first widened the "footprint" of the MF1 fitting by inserting plastic breadboards between it and MF0. Three quarters of an inch each side makes it wide enough that the bolts and washers will miss the "thing." I see no problem with strength or anything else here, but of course I'm not a structural engineer. Maybe there are marine cockroaches that eat plastic breadboards (I'm not an entymologist either) but I'm sure they would be fine.

But after some thought , I'm likely to discard MF1 together with the breadboards and opt for a simple stainless steel fabrication like an outboard engine bracket. If this is done correctly, it might be possible to do away with MF0 also, resulting in a wonderfully simple arrangement.

Anyway, it's going to take me half a day to read and digest your careful treatise on Mounting a Windpilot in the Face of Severe Handicaps Presented by the "Thing."

Incidentally, my CD27 is a late model with the Westerbeke 13 hp twin engine. I suspect it's heavier than the original, so my boat floats down by the stern. From deck level at the top of the transom to the waterline is 28 inches only. So I think I'm going to have to chop off some of the tube supporting the servo oar.

I believe we've got to the stage where none of this making any sense to anyone else and may even be irritating the heck out of them, so we'd better continue the Windpilot Wars by e-mail. Please give me a call on earthlink dot net with jvigor in front.

John V.

[Roy J.]

I believe we've got to the stage where none of this making any sense to anyone else and may even be irritating the heck out of them, so we'd better continue the Windpilot Wars by e-mail. Please give me a call on earthlink dot net with jvigor in front.

Au contraire, this is a fascinating post, a perfect demonstration of the widely divergent approaches we take to our boats. Bob has the micrometer out to avoid misalignment, and you have already drilled holes you know you will have to fill in with a later modification. I conclude that you are now both ready for Carter's symposium on celestial navigation. Warren has offered to serve as the TA. But please, really do go on, we are all bound to learn something here.

PS The backyard snow level is down to about 5 inches in Marblehead, so I guess by Saturday I will be able to access Auburn without getting a shoeful -- that means work can soon begin in earnest.

[John Vigor]

Roy, it's quite a coincidence that two CD27 owners are trying to fit brand-new Windpilot self-steering wind vanes at the same time, but I don't believe many other CD27 owners will be interested.

The snag we've come up against is quite interesting, though. Inside the lazarette of the CD27, right in the middle, up against the inner transom, is a strange web-like structure of fiberglass that we call The "Thing." I believe it must have something to do with spreading the loads of the backstay but whatever it is, it's exactly where we want to bolt our windvanes on. The bolts might just miss it on either side, but the backing washers won't.

The other problem, for me at least, is that I think the wind vane is going to look bulky and protrude too far aft. Because of the angle of the CD27's stern (about 60° from horizontal) we have to have a special extension (MF1) to the normal transom fitting for the Windpilot.

I think the whole set-up would look much neater if the vane were simply hung from a custom-made stainless steel plate. That would eliminate the special extension, and maybe even the normal transom fitting (MF0). The custom plate could be wide enough to clear the "thing" with no trouble, and it would get the whole wind-vane right up close to the transom top.

Bob seems to be trying to fit his vane with the special extension in place. He's using careful measurements, precise planning and mock-ups. I'm planning to hold my vane up to the transom when the boat comes out of the water in a couple of weeks and make a thin plywood pattern that I can take to a metal shop to be made up in 1/8th inch stainless plate. I think I can easily leave off the special extension then, and maybe even the normal extension. We shall see.

John V.

[fenixrises]

Hi intrepid windvane installers,

Here is a picture of my "thing". Although my boat is a 28 I suspect it has the same size 'Thing" as a 27. It got a bit hacked up during removal.

For general information the transom is about 1/4" thick fiberglass. The bond holding the "thing" in place adds about another 1/8" in the area of the bond.



The "thing" as it has become known to Cape Dorians. As you are looking at it in the picture it is upside down. It is the backing plate for the backstay deck mounted padeye. The plate is approx. 4" X 8" X 3/8" thick. The bars are re-bar welded to the plate. The "V" towards the camera lay against the transom and had a fiberglass bond over each leg to the inside surface of the transom. The single rod was welded to the apex of the "V". It is shorter now and bent because I cut a piece off during the process of removal. I also cut a piece of the plate off to make a through hull removal tool. As you can see the plate was not quite centered in the boat(this may be true in all installations?), as the holes for the through bolts from the padeye are biased towards one side.

Happy installing to you,
Fred B.

[John Vigor]

Fred, thanks for solving the mystery of The Thing and posting the picture. It is a strange thing, indeed, a sort of upside down mini-pyramid that probably has ancient mystical properties. It certainly repels windvanes, as Bob and I can tell you.

I had already noticed that something wasn't centered at the stern of my CD27, either the backstay or the woodwork on deck, but as I intend to give The Thing a really wide berth it doesn't actually matter.

As a matter of interest, Fred, is the metal steel or aluminum?

John Vigor
CD27 "Sangoma"
Bellingham, WA

[Bob Schwartz]

Fred:

Thanks a thousand times. You have told me just what I need to know. The picture is awesome.

As John explained, we are approaching installation a bit differently. I think mine will just fit, which means precise measurements, drilling, etc.. Further, I will have to undergo significant behavior modification and save the 6 pack until after the holes are drilled.

Thanks everyone for responding to my posts.

[fenixrises]

n/t