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Old 08-04-2020, 16:26   #1
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1967 Chinook Sloop- 34'_ Rudder Weight

I just started the refit of a 34' 1967 Chinook. I bought the boat in 2013 mid-way through a cabin/cockpit rebuild where the last owner narrowed the cockpit and switched from a Pedestal Mounted wheel to a tiller. The old owner had not gotten around to reinstalling the rudder so I am now working on finishing the job.

My problem is that the rudder weights roughly 175 lbs. It does not appear to have any water in it. I drilled 20 holes and couldn't find any moisture. I did find what appears to be a 3/8" steel plate spanning the entire rudder. Has anyone ever come across this? It seems like a crazy amount of weight for a rudder. From a structural standpoint... I assume maybe half the weight will be "hung" off the rudder bushing and half will sit on the bottom bronze rudder post receiver (?). First boat restoration, excuse my lack of correct terms.

One thing I have read is these boats can be bow heavy due to forward birth water tank.... Maybe this is a rebuilt rudder designed to shift weight back?

Any feed back is helpful. Many more posts and questions coming over the next month. Hoping to splash her for the first time in 30 years this summer.
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Old 08-04-2020, 16:32   #2
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Re: 1967 Chinook Sloop- 34'_ Rudder Weight

A heavy rudder helps to reduce weather helm, since it will sink toward the lee side when heeled. The weight also damps motion, since inertia is at play. Lastly, it's easy to build strong if weight is no concern. Strong and light--that's harder to do.
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Old 08-04-2020, 16:54   #3
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Re: 1967 Chinook Sloop- 34'_ Rudder Weight

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Originally Posted by Benz View Post
A heavy rudder helps to reduce weather helm, since it will sink toward the lee side when heeled. The weight also damps motion, since inertia is at play. Lastly, it's easy to build strong if weight is no concern. Strong and light--that's harder to do.

By my research when I made my rudder, a heavy rudder isn't what you want. Ideally you want neutral buoyancy or slightly buoyant rudder, but not really heavy rudder w/negative buoyancy.
"The near neutral buoyancy of your rudder helps the performance of your boat by reducing the total weight, as well as reducing the moment of inertia in the stern".(Foss Rudders)
Another quick primer on rudder construction

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Old 08-04-2020, 16:55   #4
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Re: 1967 Chinook Sloop- 34'_ Rudder Weight

Very classic boat, arguably the first glass production keelboat.
What is the core of the rudder? As a guess it's solid wood. Assuming that is the case put it somewhere warm and let it set for several weeks. Better yet put a heat lamp on it and let it set for several months.
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Old 08-04-2020, 18:31   #5
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Re: 1967 Chinook Sloop- 34'_ Rudder Weight

The rudder's core is 3/8" steel plate. with what looks like 1/2" plywood sandwiching both sides of steel then wrapped in fiberglass. I drilled two dozen holes all over it and left it inside for two years.... not a drop of water or weight came out of it... I think being the first production fiberglass boat they just over built the **** out of it.

Also, they located the water tank in the bow under the V-birth... not exactly where you want weight so maybe this offsets that?
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Old 08-04-2020, 19:14   #6
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Re: 1967 Chinook Sloop- 34'_ Rudder Weight

We replaced our rudder since it was replaced by a PO. It was poorly designed (a flat board) and didn't have any lift. The new rudder provided much better performance than the old one.

At this point in your rebuild, wouldn't worry too much about the rudder. Once you get it in the water and under sail, it may be perfectly fine. Can't tell by your pics, but for better lift it should be more like an airplane wing in cross section. We discuss much of this in our rudder rebuild articles on our blog.

Good luck on the rebuild.
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Old 08-04-2020, 20:09   #7
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Re: 1967 Chinook Sloop- 34'_ Rudder Weight

Since the rudder is attached, shape requirements are different than if it were a spade rudder.
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Old 08-04-2020, 20:36   #8
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Re: 1967 Chinook Sloop- 34'_ Rudder Weight

Yacht constructors built the boat
(At least the hull and rudder)
They were renamed Cascade yachts constructors.
They are now in Warrenton Oregon as cascade yacht works.
There is a cascade owners group on seaknots.
Maybe you could track down the plans.
Good luck.
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Old 08-04-2020, 20:49   #9
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Re: 1967 Chinook Sloop- 34'_ Rudder Weight

Full keel early fiberglass boats had heavy rudders. The earliest we’re just built of wood with several bronze drifts to hold them together, same as a wood boat of the same period. Once they decided to cover them in fiberglass they were essentially transitional technology and still had wood components. By the mid-sixties most had gone to steel tabs welded to the shafts, foam fillers, and fiberglass outer shells.
I just helped lift the rudder from a 1964 Pearson Vanguard into place. It still has the wood rudder and it took two of us to lift it and hold it in place so a third man could attach the tiller cap. It was built to last a lifetime and overbuilt as were all the early fiberglass hulls.
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Old 09-04-2020, 02:32   #10
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Re: 1967 Chinook Sloop- 34'_ Rudder Weight

What a beautiful looking yacht!! That looks just like Errol Flynn's yacht Sirocco! (You'll have to get a tobacco pipe!)








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Old 09-04-2020, 02:52   #11
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Re: 1967 Chinook Sloop- 34'_ Rudder Weight

Quote:
Originally Posted by Bill O View Post
By my research when I made my rudder, a heavy rudder isn't what you want. Ideally you want neutral buoyancy or slightly buoyant rudder, but not really heavy rudder w/negative buoyancy.
"The near neutral buoyancy of your rudder helps the performance of your boat by reducing the total weight, as well as reducing the moment of inertia in the stern".(Foss Rudders)
Another quick primer on rudder construction
Perhaps not. Still, a heavy rudder is not all bad, as I have shown. And the reason it was built heavy I have also demonstrated. Whether that's an ideal design or not is up to the OP to judge.
As far as lift, I'm willing to be corrected, but I don't think a foil shape does much to generate lift on an attached rudder.
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Old 09-04-2020, 07:41   #12
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Re: 1967 Chinook Sloop- 34'_ Rudder Weight

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Originally Posted by Adelie View Post
Since the rudder is attached, shape requirements are different than if it were a spade rudder.
Somewhat, but you still need a taper to develop lift. Our skeg held rudder is not that much different than attachment to the full keel and it did benefit greatly w/the NACA 0010 design (the new rudder). The old rudder (replaced by a PO) was a flat, heavy wooden board covered w/f/g and didn't develop any appreciable lift. The lack of lift (rudder stalled) made the boat difficult to steer in heavy air. The new rudder was an amazing difference in handling.

Quote:
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Perhaps not. Still, a heavy rudder is not all bad, as I have shown. And the reason it was built heavy I have also demonstrated. Whether that's an ideal design or not is up to the OP to judge.
As far as lift, I'm willing to be corrected, but I don't think a foil shape does much to generate lift on an attached rudder.
As explained above the foil or tapered shape does work much better to create lift even on a boat w/skeg or full keeled held rudder. Did a lot of research on rudder design and had discussions w/several well know NAs on this subject. You don't see much lift when the rudder is straight behind the dead wood. As you start add more rudder angle this is where you need the lift to sail and counter the boat wanting to round up. A flat rudder is the worst shape possible for sailing purposes, but works for most power boats.

The rudder we made was somewhat designed after the semi-balanced rudder that is found on some boats, including "newer" Bristols. Will say our new rudder was a night/day difference in handling.
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Old 09-04-2020, 08:00   #13
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Re: 1967 Chinook Sloop- 34'_ Rudder Weight

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Originally Posted by coopec43 View Post
What a beautiful looking yacht!! That looks just like Errol Flynn's yacht Sirocco! (You'll have to get a tobacco pipe!)








https://sailboatdata.com/storage/images/sailboat/photo/chinook_34_photo.jpg
Thanks for posting the original diagram which included the rudder.

Looking at the OP's rudder, I now see that the new rudder is much larger (more surface area) than the original one. This may help steer the boat better in certain conditions, but the added extra surface in lower aft section of the rudder will possibly add some heaviness to the tiller. While he will have no comparison to the original rudder, it will be interesting to hear how the boat sails. Typical w/that era boat (large main/long foot), will need to reef early to control WH.


OP looking at the pic of your rudder, is the metal plate on the bottom of the rudder section? If so, this may have been an attempt to create a neutrally buoyant rudder. Again can't tell by the pic, but it does look as if rudder is tapered. If it were me, I'd go w/that rudder to see how it works before fussing w/it.
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Old 09-04-2020, 11:44   #14
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Re: 1967 Chinook Sloop- 34'_ Rudder Weight

Quote:
Originally Posted by pdxsailordiver View Post
Yacht constructors built the boat
(At least the hull and rudder)
They were renamed Cascade yachts constructors.
They are now in Warrenton Oregon as cascade yacht works.
There is a cascade owners group on seaknots.
Maybe you could track down the plans.
Good luck.
No. Philbrooks did in Victoria B.C. starting in 1974. Nowhere near the first production fiberglass cruiser. Designed ny Stan Huntingford.
https://sailboatdata.com/sailboat/chinook-37

Call Philbrooks - they are still in business and well respected in this area.
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Old 09-04-2020, 11:57   #15
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Re: 1967 Chinook Sloop- 34'_ Rudder Weight

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Originally Posted by mitiempo View Post
No. Philbrooks did in Victoria B.C. starting in 1974. Nowhere near the first production fiberglass cruiser. Designed ny Stan Huntingford.
https://sailboatdata.com/sailboat/chinook-37

Call Philbrooks - they are still in business and well respected in this area.
OP boat is a 1967 Chinook 34.
Different boat first built in early 1950’s.
Really incredible story, 3 people who started the company and had no boat building experience. Really no plans other then build 3 boats.
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