I want to mount a schaefer series 300 cheek block on the top of my C22 sport in order to run my main halyard aft. For fasteners, Defender marine recommends 4 #10 rh. I am not sure what these are. Do I need to drill through the cabin top and use ss bolts with nuts and washers, or will 4 screws be sufficient. Thanks for any help or advice. Chuck Turner
Mounting a cheek block
- Thread starter Chuck Turner3968
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I assume Defender is recommending
using 4 #10 round head (rh) machine screws to mount whatever hardware you plan to use on deck to bring the halyard back to the cockpit. These screws are two sizes smaller than a 1/4-in bolt and come in coarse or fine threads per inch. Make sure you buy the matching thread size for the nuts. I would assume a turning block would be a better choice than a cheek block, but I'm not familiar with your deck layout. You would be far better through-bolting these screws, with nuts and large fender washers on the underside. Make sure you seal the holes drilled with the appropriate caulk.
using 4 #10 round head (rh) machine screws to mount whatever hardware you plan to use on deck to bring the halyard back to the cockpit. These screws are two sizes smaller than a 1/4-in bolt and come in coarse or fine threads per inch. Make sure you buy the matching thread size for the nuts. I would assume a turning block would be a better choice than a cheek block, but I'm not familiar with your deck layout. You would be far better through-bolting these screws, with nuts and large fender washers on the underside. Make sure you seal the holes drilled with the appropriate caulk.
A short course in hardware:
Machine screws have threads that are the same as the threads on bolts. All machine screws and bolts are designated by size first and then by the number of threads per inch. Thus you get from the very small to the very large. #2-72 is a very small screw 100 of them a 1/4 inch long would fit on a teaspoon. From there the sizes go 4-40, 6-32, 8-32, 10-24 & 10-32, 12-24, 1/4-20 & 1/4-28 etc. The sizes run up to where one bolt is a load to carry. You can purchase Fine thread bolts and Course thread bolts. The label will indicate 10-24 NC or 10-32 NF etc. Bolt and screws also come in a variety of head styles Round head stands proud on the surface, Flat head has a cone shape underside and requires a counter sink to make it fit properly (hinge screws are an example)Oval head screws are like a flat head screw but the top of the head is a little rounded. After this comes the familar square head and hexagon heads on bolts. I hope this is more help than harm .
Machine screws have threads that are the same as the threads on bolts. All machine screws and bolts are designated by size first and then by the number of threads per inch. Thus you get from the very small to the very large. #2-72 is a very small screw 100 of them a 1/4 inch long would fit on a teaspoon. From there the sizes go 4-40, 6-32, 8-32, 10-24 & 10-32, 12-24, 1/4-20 & 1/4-28 etc. The sizes run up to where one bolt is a load to carry. You can purchase Fine thread bolts and Course thread bolts. The label will indicate 10-24 NC or 10-32 NF etc. Bolt and screws also come in a variety of head styles Round head stands proud on the surface, Flat head has a cone shape underside and requires a counter sink to make it fit properly (hinge screws are an example)Oval head screws are like a flat head screw but the top of the head is a little rounded. After this comes the familar square head and hexagon heads on bolts. I hope this is more help than harm .
Generally speaking Chuck, you should never use 'screws'
to mount load bearing hardware on your boat. The exception is if the deck or wherever had an embedded plate with threads already cut into it for the attachment of screws. I'm not familiar enough with Catalinas to say whether they have embedded plates so the advice would be to carefully drill through the deck as stated earlier and use fender washers and nylock nuts (of the #10 size). Seal the hole with appropriate caulk and tighten until snug - don't overtighten as this may crack the gelcoat and interior liner. Good Luck!
to mount load bearing hardware on your boat. The exception is if the deck or wherever had an embedded plate with threads already cut into it for the attachment of screws. I'm not familiar enough with Catalinas to say whether they have embedded plates so the advice would be to carefully drill through the deck as stated earlier and use fender washers and nylock nuts (of the #10 size). Seal the hole with appropriate caulk and tighten until snug - don't overtighten as this may crack the gelcoat and interior liner. Good Luck!
Being a bit anal here , There is generally an acceptance
of the use of bolt or screw when referring to threaded fasteners. Screws are more generic and can refer to small bolts, wood screws, sheet metal and drywall screws, set screws can be made with a socket, a slot or with a square head. They make lag bolts/screws as large as 1 inch and wood screws as small as a number 1 size found in old clocks.
of the use of bolt or screw when referring to threaded fasteners. Screws are more generic and can refer to small bolts, wood screws, sheet metal and drywall screws, set screws can be made with a socket, a slot or with a square head. They make lag bolts/screws as large as 1 inch and wood screws as small as a number 1 size found in old clocks.
Length of ss bolts/screws
Thanks to all for the info. One other quick question. Any suggestions as to length of the through bolts/screws. Obviously, I can drill through and then measure the depth of the hole, but I am hoping someone is familar with the thickness of the top of the cabin and knows the length. Chuck
Thanks to all for the info. One other quick question. Any suggestions as to length of the through bolts/screws. Obviously, I can drill through and then measure the depth of the hole, but I am hoping someone is familar with the thickness of the top of the cabin and knows the length. Chuck
You'll need an assortment, there's no
magic suggestion. The thickness of the deck can vary significantly even on just your boat. When we did ours on our C22 years ago, I bought an assorted length of machine screws, and either kept the ones I didn't use or returned them. Don't know what you have down below or where the screws will come out, but I recall if its near the mast you may be sitting around there. Many of us use fender washers with lock washers capped with cap nuts (or regular nuts with cap nuts), which avoids having the raw shaft of the machine screw sticking out down below. West Marine's catalog has a very good decsription of fasteners in the Deck Hardware section.
magic suggestion. The thickness of the deck can vary significantly even on just your boat. When we did ours on our C22 years ago, I bought an assorted length of machine screws, and either kept the ones I didn't use or returned them. Don't know what you have down below or where the screws will come out, but I recall if its near the mast you may be sitting around there. Many of us use fender washers with lock washers capped with cap nuts (or regular nuts with cap nuts), which avoids having the raw shaft of the machine screw sticking out down below. West Marine's catalog has a very good decsription of fasteners in the Deck Hardware section.
Thanks Stu
Thanks Stu. I am in Destin, FL through March so I will go down to West Marine and get an assortment of #10 bolts and nuts. I had also thought of the cap nuts to clean up the installation in the cabin. Because the holes in the curved mounting plate of the cheek block are fairly close together (9/16ths center to center), I will probably fabricate a stainless backing plate, because I think washers will be too close together. Again, thanks to all who responded to my inquiry. This is a great forum for beginning sailors like myself. Chuck
Thanks Stu. I am in Destin, FL through March so I will go down to West Marine and get an assortment of #10 bolts and nuts. I had also thought of the cap nuts to clean up the installation in the cabin. Because the holes in the curved mounting plate of the cheek block are fairly close together (9/16ths center to center), I will probably fabricate a stainless backing plate, because I think washers will be too close together. Again, thanks to all who responded to my inquiry. This is a great forum for beginning sailors like myself. Chuck
Ace Hardware would be a Good Source for your Screws
Of course you can't get all sorts of tips from Beatty there. Canvas Specialties on Hollywood is a great place to get you backing plate made. I wonder if making a larger plate 2" across or so mounting the cheek block to that and then mounting that to the cabin top would be a better way to go.
Of course you can't get all sorts of tips from Beatty there. Canvas Specialties on Hollywood is a great place to get you backing plate made. I wonder if making a larger plate 2" across or so mounting the cheek block to that and then mounting that to the cabin top would be a better way to go.
Our ACE hardware has a special
stainless steel fastening section, where all the stuff is in flat drawers compared to the cheap screws sitting in plastic boxes on pins hanging on a wall. Check their selection, but a good hardware store should have quality stainless, too, separate from the junk and probably less $$ than WM. OTOH, for a few, it shouldn't amount to a big $$ difference.
stainless steel fastening section, where all the stuff is in flat drawers compared to the cheap screws sitting in plastic boxes on pins hanging on a wall. Check their selection, but a good hardware store should have quality stainless, too, separate from the junk and probably less $$ than WM. OTOH, for a few, it shouldn't amount to a big $$ difference.
Make sure...
you use a fender washer and double nut the underside. Actually... if you could find a cap nut/acorn nut for 2nd nut installed, that would be great... so you don't rip your forehead off. Rich
you use a fender washer and double nut the underside. Actually... if you could find a cap nut/acorn nut for 2nd nut installed, that would be great... so you don't rip your forehead off. Rich
While reading this thread...
I saw the term "appropriate caulk". Yet, no one defined what "appropriate caulk" is. There are how many different types of caulk? Wouldn't it be better if one is to give a lot of good info, one would ensure that one defines everything being used. Not everyone knows what is considered "appropriate caulk". This isn't a complaint, just an observation.
I saw the term "appropriate caulk". Yet, no one defined what "appropriate caulk" is. There are how many different types of caulk? Wouldn't it be better if one is to give a lot of good info, one would ensure that one defines everything being used. Not everyone knows what is considered "appropriate caulk". This isn't a complaint, just an observation.
Brian in responce , I would say that it is easier to
note the caulks that are inappropriate. 3M 5200 would be #1. Silicone comes in close. Water clean-up caulks are good if you can be sure of no rain for a couple of days. Sikaflex is always a good choice and there are others whose name doesn't come readily to mind. Being able to remove the piece at a later date is the first consideration. Being able to seal a new one in place of the old is also important. This block will have some stress applied to if so the caulk should be flexible. The label is a good place to start when you select any material for a job.
note the caulks that are inappropriate. 3M 5200 would be #1. Silicone comes in close. Water clean-up caulks are good if you can be sure of no rain for a couple of days. Sikaflex is always a good choice and there are others whose name doesn't come readily to mind. Being able to remove the piece at a later date is the first consideration. Being able to seal a new one in place of the old is also important. This block will have some stress applied to if so the caulk should be flexible. The label is a good place to start when you select any material for a job.
Counterbore
Chuck, Suggest you first counterbore hole location appx. 1/16 - 1/8" deep with flush head point drill at least 2x the diameter of the screw/bolt you will be using. The surface finish on some decks is softer antiskid material which will climb the drill if there is no counterbore. You will end up with a "bump" in the deck surface around the hole when not counterbored. Also the counterbore provides a nice pocket for the caulking/sealant. Be sure to drill counterbore first, so that the hole center will be the same as the counterbore center. BobD
Chuck, Suggest you first counterbore hole location appx. 1/16 - 1/8" deep with flush head point drill at least 2x the diameter of the screw/bolt you will be using. The surface finish on some decks is softer antiskid material which will climb the drill if there is no counterbore. You will end up with a "bump" in the deck surface around the hole when not counterbored. Also the counterbore provides a nice pocket for the caulking/sealant. Be sure to drill counterbore first, so that the hole center will be the same as the counterbore center. BobD
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