CD 27 Engine - Do I have a YSB8 or YSB12?

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Tailwind
Posts: 5
Joined: Jul 22nd, '20, 13:12
Location: CD 27 No. 52 Sea Lilly, Oriental, NC

CD 27 Engine - Do I have a YSB8 or YSB12?

Post by Tailwind »

Hi Cape Dory forum folk,

This is my first post. I'm the happy owner of a new-to-me 1977 CD 27 "Sea Lilly". I'm taking care of deferred maintenance: getting stuck seacocks moving, new hoses on all seacocks, new belts on the engine, lifelines, new compass, canvas repair, etc. I'm finding a wealth of helpful info here on the forum.

The boat seems under-propped. At 2200 RPM on flat water she'll make 2.3 knots. Prop is a 2 blade. I'm not sure of the size/pitch. Bottom of the boat was cleaned a month ago.

Before I shop for a new prop, It would be good to know which engine I have. From what I read, the boat would have probably come with a Yanmar YSB8. However, the ID plate on the transmission reads "YSB12". I haven't found a serial number on the engine block. Is there a way to be sure the engine is a YSB12? Could I have an YSB8 with the transmission from a YSB12?

ID tag on transmission:

Image

Image

Thanks!
fmueller
Posts: 475
Joined: Mar 15th, '14, 08:25
Location: "Jerezana" CD 27

Re: CD 27 Engine - Do I have a YSB8 or YSB12?

Post by fmueller »

Well that badge is pretty convincing -

Here is an old Yanmar product sheet. The 12 is dimensionally larger and the mounts are a little larger as well ... you should be able to determine with carefully measuring engine width for instance ...


http://sailingthanksdad.com/documentati ... ochure.pdf
Fred Mueller
Jerezana
CD 27 Narragansett Bay
Tailwind
Posts: 5
Joined: Jul 22nd, '20, 13:12
Location: CD 27 No. 52 Sea Lilly, Oriental, NC

Re: CD 27 Engine - Do I have a YSB8 or YSB12?

Post by Tailwind »

Fred,

After carefully measuring, it's pretty clear that I have a YSB8 engine with the transmission from a YSB12.

Thanks so much for your help!

Steven
Walter Hobbs
Posts: 202
Joined: Sep 22nd, '14, 08:34
Location: CD 14,CD 27

Re: CD 27 Engine - Do I have a YSB8 or YSB12?

Post by Walter Hobbs »

Greetings,

I have CD 27 hull # 35. YSB8 original to the boat as far as I can tell. 2 blade prop easily pushes her to 5 knots. You say bottom is clean does prop have any growth? I don't have prop pitch or diameter handy, my notes are on the boat. I'll check. Interesting puzzle. Different gear ratio in YSB12 transmission??
Walter R Hobbs
CD 14 hull # 535, Grin
CD 27 Hull # 35 Horizon Song
Lincoln, RI

"Attitude is the differance between ordeal and adventure."
fmueller
Posts: 475
Joined: Mar 15th, '14, 08:25
Location: "Jerezana" CD 27

Re: CD 27 Engine - Do I have a YSB8 or YSB12?

Post by fmueller »

Good guess Walter. Wonder if a previous owner fit the 12 transmission as a repair and inadvertently raised the reduction ratio. That could account for lack of speed. As if you are stuck in 1st gear - prop never spins fast enough. A very powerful car for instance would not have top speed if it could only use first gear. Acceleration maybe.

Even wilder guess. What if there’s a wrong handed prop mounted and the forward and reverse control cables are swapped. Some transmissions have really steep reverse reduction.
L
Last edited by fmueller on Aug 9th, '20, 20:11, edited 1 time in total.
Fred Mueller
Jerezana
CD 27 Narragansett Bay
Walter Hobbs
Posts: 202
Joined: Sep 22nd, '14, 08:34
Location: CD 14,CD 27

Re: CD 27 Engine - Do I have a YSB8 or YSB12?

Post by Walter Hobbs »

Fred,
Per the data sheet you posted, looks like reduction ratios for both engines are the same. Guess that's not it.
Walter R Hobbs
CD 14 hull # 535, Grin
CD 27 Hull # 35 Horizon Song
Lincoln, RI

"Attitude is the differance between ordeal and adventure."
Tailwind
Posts: 5
Joined: Jul 22nd, '20, 13:12
Location: CD 27 No. 52 Sea Lilly, Oriental, NC

Re: CD 27 Engine - Do I have a YSB8 or YSB12?

Post by Tailwind »

@fmueller Interesting wild idea. I checked the movement of the shift lever/transmission lever. It moves as it should - moving the shift lever forward puts the transmission into ahead; moving it aft puts the transmission into astern.
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