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pastmember
Master Marine Consultant

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2402 Posts
Response Posted - 10/09/2017 :  14:55:49  Show Profile
Measure your mast step and search on Defender and West, see what you come up with. C25s should use 5 series blocks at the mast. The photo is of my Starwind 225, I used 3 series blocks on her.

'82 swinger


'89 wing
Frank Hopper
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sethp001
Mainsheet C-25 Tech Editor

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814 Posts
Response Posted - 10/09/2017 :  18:52:14  Show Profile
quote:
Originally posted by Dave5041

quote:
Oh, and by the way, according to my highschool geometry teacher, Mr. K, a 45° angle will result in 70% of the force of a straight vertical.


The simple sum of vector forces when the angle of application is not considered will exceed the actual applied force. The sine and cosine of 45º are equal. 100 pounds of force applied at a 45º vectors to 70# vertical and 70# horizontal.

edit: Multiplying the vectored forces by the appropriate angle functions and summing will result in 100 # of applied force, as you would expect since we're using the same values.


How does this work? Would not 100 lbs of force at 45º result in 50 lbs vertical and 50 lbs horizontal?


Seth
"Outlier" 1987 Catalina 25 SR/SK/Traditional Interior #5541
"Zoo" 1977 Morgan Out Island 30
"Nomad" 1980 Prindle 16
"Lost" 1988 Catalina Capri 14.2 (sold - yay!)
"Marine Tex 1" Unknown Origin POS 8' Fiberglass Dinghy
https://whichsailboat.com/2014/07/27/catalina-25-review/
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Captmorgan
Navigator

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USA
220 Posts
Response Posted - 10/10/2017 :  04:16:20  Show Profile
Let me know its perfect for my need if you don't use it
"The Gal-Way" 1985 SR/SK Barnegat Bay, NJ

Enjoy Sailing =) Be Safe

Happy Sailing - John




Photo Album
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Captmorgan
Navigator

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USA
220 Posts
Response Posted - 10/10/2017 :  04:18:16  Show Profile
Thanks for the pics

quote:
Originally posted by sethp001

quote:
Originally posted by Dave5041

quote:
Oh, and by the way, according to my highschool geometry teacher, Mr. K, a 45° angle will result in 70% of the force of a straight vertical.


The simple sum of vector forces when the angle of application is not considered will exceed the actual applied force. The sine and cosine of 45º are equal. 100 pounds of force applied at a 45º vectors to 70# vertical and 70# horizontal.

edit: Multiplying the vectored forces by the appropriate angle functions and summing will result in 100 # of applied force, as you would expect since we're using the same values.


How does this work? Would not 100 lbs of force at 45º result in 50 lbs vertical and 50 lbs horizontal?
"The Gal-Way" 1985 SR/SK Barnegat Bay, NJ

Enjoy Sailing =) Be Safe

Happy Sailing - John




Photo Album
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Dave5041
Former Mainsheet Editor

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USA
3754 Posts
Response Posted - 10/10/2017 :  09:43:06  Show Profile
quote:
How does this work? Would not 100 lbs of force at 45º result in 50 lbs vertical and 50 lbs horizontal?


Correct, you must include all factors (force and angle functions) and multiply before adding. COS and SINE x the vectored forces equals 50 and 50 which sums to the applied force.

Applied Force x COS 45º, SINE 45º = Vectored Horizontal force x COS 45º + Vectored Vertical Force x SINE 45º

Dave B. aboard Pearl
1982 TR/SK/Trad. #3399
Lake Erie/Florida Panhandle
Edited by - Dave5041 on 10/10/2017 09:55:32
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Dave5041
Former Mainsheet Editor

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USA
3754 Posts
Response Posted - 10/10/2017 :  10:15:58  Show Profile
Thanks Frank, I thought that might be a risk and intended to stress test it before installing since I use 1/4" Vectran for my main halyard, a slippery line.

Dave B. aboard Pearl
1982 TR/SK/Trad. #3399
Lake Erie/Florida Panhandle
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pastmember
Master Marine Consultant

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2402 Posts
Response Posted - 10/10/2017 :  10:19:18  Show Profile
quote:
Originally posted by Dave5041

Thanks Frank, I thought that might be a risk and intended to stress test it before installing since I use 1/4" Vectran for my main halyard, a slippery line.


Vectran will definitely slip. Voice of experience.
Frank Hopper
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sethp001
Mainsheet C-25 Tech Editor

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814 Posts
Response Posted - 10/10/2017 :  13:51:52  Show Profile
quote:
Originally posted by Dave5041

quote:
How does this work? Would not 100 lbs of force at 45º result in 50 lbs vertical and 50 lbs horizontal?


Correct, you must include all factors (force and angle functions) and multiply before adding. COS and SINE x the vectored forces equals 50 and 50 which sums to the applied force.

Applied Force x COS 45º, SINE 45º = Vectored Horizontal force x COS 45º + Vectored Vertical Force x SINE 45º


Thanks, Dave!


Seth
"Outlier" 1987 Catalina 25 SR/SK/Traditional Interior #5541
"Zoo" 1977 Morgan Out Island 30
"Nomad" 1980 Prindle 16
"Lost" 1988 Catalina Capri 14.2 (sold - yay!)
"Marine Tex 1" Unknown Origin POS 8' Fiberglass Dinghy
https://whichsailboat.com/2014/07/27/catalina-25-review/
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Justin_gee
Deckhand

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USA
1 Posts
Response Posted - 10/12/2017 :  12:31:47  Show Profile
quote:
Originally posted by pastmember

Use the mast bolt




Anyone else break the hound on the boomvang? Mine snapped after 25 years while out this past week. Was just going to replace it with a new hound (~$15) and then re-screw it back in. But wondered if there was a better way.

Dlucier solved this problem a while back



Schaefer Marine part 90-08, about $40, 3.75" wide by 4" deep. This is on a C-25 Tall Rig (so the mast is a bit bigger than a standard one). You need a 5" 3/8-16 bolt (and a hacksaw to trim that extra bolt length) to avoid having any threads in the mast.

http://catalina-capri-25s.org/forum/topic.asp?ARCHIVE=true&TOPIC_ID=26208
Justin Gee
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Notice: The advice given on this site is based upon individual or quoted experience, yours may differ.
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