Counting is most of the job
The default boat on this form has nine through-hulls: four small ones on half-inch hose, three on three-quarter, and two big ones on inch-and-a-half. That is a fairly ordinary count for a 35 ft cruiser and it produces 50 ft of hose and 36 clamps once you allow two ends per fitting and two clamps per end.
Thirty-six clamps is the number that surprises people. Clamps are the cheapest thing on the list and the item most often reused past the point where reusing them makes sense, and the count is high because every hose has two ends and good practice puts two clamps on each of them.
The ends field is doing real work
Two ends per fitting is the simple case: seacock to equipment, one hose, two joints. A raw water circuit that runs seacock to strainer to pump has four ends on the same fitting, and an air conditioning loop can have more. The field is there because the clamp count is entirely driven by joints rather than by holes, and getting it wrong understates the parts list by half.
The same applies to hose length. Measured with a tape between two points, a run reads short every time. Measured with a piece of string laid along the route the hose has to take — around the stringer, over the engine, under the sole — it reads what you actually buy.
Replacing a quarter at a time
Nobody does all nine in one haul-out unless something has gone badly wrong. The form takes a share instead, and rounds each group up, so 25 percent of the default boat is three fittings rather than 2.25. Those three are 3.75 hours at 75 minutes each, and 546 dollars of parts before sealant.
The full-system figure is printed alongside it deliberately. Seeing that the whole boat is about 1,600 dollars of parts and 11 hours is the thing that decides whether a rolling programme or one big job makes more sense — and the answer depends far more on access than on money. Two of the nine are usually easy and two are usually miserable.
The interval is yours, not this page
The form asks for a replacement interval and an age, and prints the difference back. That is a restatement of your own plan, and it is deliberately not advice. No service life for any fitting is stated here, because service life depends on material, installation, water, electrical environment and how the boat has been used, and none of those are visible to arithmetic.
What condition looks like is a job for a surveyor with a torch and a screwdriver, and it is the only method that finds the fitting that failed early. The list on this page is what to buy once somebody who can see the boat has told you what needs doing.
Questions people ask
How many through-hulls does a typical sailboat have?
More than the owner remembers. Engine intake, head intake and discharge, sink drains, cockpit scuppers, bilge and shower outlets, washdown, air conditioning and transducers add up quickly, and nine is unremarkable on a 35 footer. The only reliable count is a walk round the boat with a torch, because the ones behind tanks and under berths are the ones people forget.
How many hose clamps do I need per fitting?
The count comes from joints rather than holes: ends per fitting times clamps per end. On the default settings that is two ends and two clamps, so four per fitting and 36 across nine fittings. A circuit that runs through a strainer has four ends, not two, which doubles it — that is why the ends figure is a field rather than an assumption.
How much does it cost to replace seacocks?
For the default figures — 110 dollars a fitting, 9 dollars a foot of hose and 4.50 a clamp — three fittings comes to 546 dollars of parts and the whole nine-fitting system to about 1,600, before sealant, labour or the haul-out itself. Prices are placeholders on this form and should be replaced with what your chandlery charges.
How often should through-hulls be replaced?
This page states no interval and will not, because service life depends on the material, the installation, the water and the electrical environment aboard. The form takes your own interval and your own age as inputs and subtracts them, which restates your plan rather than judging it. Whether a fitting is due is what a surveyor determines by inspection.
Why does the list include tapered plugs?
Because a fitting below the waterline that fails floods the boat, and it commonly does it when nobody is aboard. The count is one per fitting plus whatever spares you set, which is why the form asks separately how many of the fittings are below the waterline. That is as far as this page goes on the subject — it names the hazard and gives no procedure.