Please Visit: https://marinehowto.com/
This old format has run its course and the new web site is now up and running. Articles here will no longer be kept current, or up to date, and eventually this site will go the way of the buggy whip.
Please change your bookmarks and visit the new site. See new links below.
Anatomy of A Tapered Cone Seacock
These are the parts of a Spartan Marine tapered cone or tapered plug seacock. Over the years there were many brands of tapered cone seacocks but only two that I know of remain, Spartan in Maine and Blakes over in Europe.
At one time there were Spartan, Blakes, Groco, Wilcox Crittenden, Buck Algonquin and others that all made this type of seacock.
Anatomy of A Tapered Cone Seacock 2
In this photo we can see the cone or plug and the taper is evident. The valve body has a corresponding taper in it and the two are lap fit or ground to fit and mate nearly perfectly.
The beautiful thing about these robust bronze seacocks is they are made from the same material, all 85-5-5-5 bronze. Eightyfive-three-five bronze is made up of; 85% Copper, 5% Tin, 5% Lead (for machining ease) and 5% Zinc. It is one of the most corrosion and dezincification resistant forms of bronze used in the marine industry.
In contrast most propellers & Prop struts are made of a Manganese Bronze which is anywhere between 26% & 40% Zinc. Which of these "bronze" materials do you think will last longer in the marine environment? There are no dissimilar materials in most tapered cone/plug seacocks unlike a gate valve or ball valve, even a marine UL ball valve has dissimilar metals..
In this photo we can also see the dog washer flat spots. This dog washer rides around the valve body with the cone and the dog creates positive stops on either side. There are matching dogs cast into the body of the valve.
When re-installing the cone the flat spot should be facing up. This allows you to see the actual orientation of the valve hole by looking at the dog. The flat spot is in-line with the cone/plug hole and the valve body dogs are designed for this orientation at 12:00 when open.
If you install the dog upside down at 6:00 you will bend the dog on the valve body dogs as they are only machined flat on top and have a ramp or slope on the bottom that will bend an improperly installed dog washer.
All Spartan seacocks have dog washers and valve body stop dogs. Despite what many Cape Dory owners believe are Spartan seacocks they can often be Wilcox Crittenden seacocks. Cape Dory used WC seacocks when they ran out of Spartans or could not get them in time. If you don't have dog ear washers your valves are likely not Spartans.
Anatomy of A Tapered Cone Seacock 3
In this photo you can see the machined groves in the bottom of the valve body. They are machined in to help retain a marine sealant and thus prevent leaks.
You can also see the proper placement of the Jam/Jamb nut and flange nut. I purposely placed the dog washer on backwards to show what NOT to do. The dog should always face the valve body and with valve open be oriented at 12:00.
UL Marine Label
It should go without saying but when doing below the waterline seacock/sea valve work the parts should be UL Marine labeled.
Groco, Spartan, Forespar/Marelon, Apollo/Conbraco, Buck Algonquin and others all sell UL Marine rated seacocks & valves. If it does not say UL Marine, or come from a legitimate manufacturer, you would be best to purchase other products that do meet the stringent UL Marine testing standards.
Brand New Spartan Seacock
This is a brand new Spartan Seacock. These are wonderful and expensive products that can last well into 30+ years. According to Paul at Spartan the "average" life he sees is 30 years. Keep in mind though that many of these "average" valves have not been routinely maintained.
Tapered cone seacocks if cleaned & greased yearly, and lapped when needed, can likely out last you. Sadly many don't service them regularly and they then need replacement sooner.
These seacocks were installed by many reputable builders such as Sabre, Pearson, Tartan, C&C, Cape Dory, Bristol, Hinckley, Morris, Shannon Yachts and others. Today very few builders other than Robinhood/Cape Dory and Shannon still use them though there are a few Down East Maine builders who will still use nothing but. With price competition the way it is builders have moved to less expensive, though not necessarily better, alternatives.
If servicing Spartan seacocks you'll need two 15/16" wrenches or a 15/16" wrench and a smaller 3/4" wrench for the smaller size jam nuts on the 3/4" valves.
It's important to note that you will need a thin "spanner" type wrench as the flange nut is thinner than most 15/16" wrenches. The Wilcox Crittenden valves will take a full thickness 15/16" wrench on the flange nut but the Spartans will not.
What I did is simply grind down a Harbor Freight quality 15/16" wrench on my bench grinder to fit the Spartan flange nut. If your wrench is to thick you won't be able to effectively "lock" the two nuts together and they may work loose.
If you click on this picture, to make it larger, you can see where I ground this wrench thinner to fit the jam nut. This took about 5 minutes on a bench grinder and I think I paid about $3.00 for the wrench.
Of course if you're lucky enough to own a vessel with Spartan seacocks then you might want to spring for their 316 stainless steel seacock wrench. I own one and it is worth it as the length is just right.
It also has a hole in the end for a lanyard so you don't drop it into the black hole that is your bilge!
Grease is grease right? Well, no, it's not. Over the years when I have been out of the Spartan Seacock grease I have tried everything from standard white lithium grease to expensive synthetic grease like Morey's Red or Amsoil waterproof synthetic grease. None of these wonder greases has worked nearly as well, or lasted as long, as the grease sold by Spartan Marine.
This white lithium based grease is THICK because it can be. Picture cold peanut butter and you'll have the consistency about right. Spartan has added some proprietary and "top secret" Tony the Tiger like ingredients that actually DO WORK. Trailer bearing grease is thinner, because it has to be. These valves only ever turn up and down maybe 60 times per year, they are not spinning at 70MPH while driving 100 miles to a boat launch ramp. Because these valves rotate less than a full revolution the grease can be significantly thicker for the application, and it just works.
Spartan is fairly adamant that you not use a synthetic grease and I can concur with their suggestion. Many Cape Dorian's swear by Morey's Red but I still find the Spartan grease to out perform it fairly handily. I find synthetics get hard, have less "film thickness" and the valves leak sooner and turn harder sooner than when I use genuine Spartan seacock grease.
The grease is about $12.00 for a tub that will last many years.
Every so often the tapered cones/plugs need to be lap fit with lapping compound or basically liquid sandpaper. The Spartan Lap Compound is a 320 grit silicon carbide in an oil/grease base. It works very well and is specifically made by Spartan for their seacocks.
You can also buy lapping compound made by Loctite, it's called Clover Compound, in a 320 grit formula but it is actually more expensive than the Spartan stuff.
My only complaint with the Spartan compound is that the oil and silicon carbide separate and it needs to be stirred well with each use.
1- First use the two wrenches to loosen the jam nut from the flange nut.
2-Remove jam nut, flange nut and dog washer from the cone/plug shaft and set aside. Some brands like the old Wilcox Crittenden seacocks did not have "dogs" on the washer. Many a tapered cone owner, myself included, have dropped jam nuts, flange nuts or the dog washer into the bilge during removal or re-installation. A wise man once suggested to me to wrap a towel around the base of the seacock when removing the pieces. This prevents the old "bounce & slide" disappearing act. On some boats if you drop a part they are gone forever!
3-Use handle to move valve and the cone/plug will pop out.
4- If the valve was stuck a light tap on the nut end, with a hardwood mallet, will almost always free the cone from the valve body. If you do not have a hardwood mallet just leave the jam nut 90% on and tap on the nut. This will prevent you from damaging the threads on the cones shaft. DO NOT beat on it.
5- Use a good grease cutting solvent & a rag, I like odorless mineral spirits, to thoroughly clean the inside of the valve body.
A Nasty Cone/Plug
Ideally you want the most contact area you can get. I try for about 80-90% minimum contact area between the valve body and the cone/plug but on some cones that is not even possible.
Here we have what looks to be less than 30% contact and the valve had been leaking. Even a thorough cleaning and greasing may have only stopped the leaking for a short while, and it needed to be lap fit. Keep in mind that the main goal here is simply no weeping when open or closed. If 60% contact area in the right spots does it, then you're good to go.
It should be noted that this Spartan Seacock was 32 years old. Show me even one 32 year old ball valve in the marine environment still working and I'd be very surprised. This is why I like Groco's flanged adapter so much. Ball valves just do not last like a true tapered cone seacock does.
In-frequent servicing leads to sea-crud build up in the spot on the cone when it is in the closed position. When you then move the valve it carries this abrasive crud into the valve body thus wearing it down. If you grease annually, and open your valves properly, as in 100% open, not just partially open, you can minimize this wear and prolong the time between lap fitting.