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>You will notice that when they first built the rudder they used ordinary carbon steel for the support and welded it to a Stainless shaft.
Ralph, you are probably much more savvy about metal than I am, but is it not true that even the best stainless will rust or corrode if it's in oxygen-free salt water, producing the greasy brown crud that we're talking about here?
I don't entirely understand the mechanism, but I thought stainless steel was rather like aluminum, which forms a protective oxide on an exposed surface. Therefore, if there is no water circulation (and water that has seeped into a rudder is not going to circulate), the water's oxygen will become exhausted, the protective oxide will disappear and corrosion will begin in earnest, even with the best quality of stainless steel. True or not?
David Weatherston
"Towser", Toronto
C&C 27 Mk IV
No
David Weatherston
"Towser", Toronto
C&C 27 Mk IV
1. It seldom helps unless the dealer is a real electronics dealer, but have you spoken to them? Does Standard Horizon have a web site with tech help?
2. Do your depth cables have cylindrical objects near the termination point? These are intended to reduce radio frequency interference. My Raymarine unit has them. Perhaps you can get some of these?
3. Do you have or can you get a copy of Boatowner's Mechanical and Electrical Manual by Nigel Calder? He gives about three pages of suggestions (including resistor plugs) on how to deal with RF at the source. Calder claims an electronics-whiz friend of his says dealing with RF any other way is like taking aspirin for a brain tumour.
David Weatherston
"Towser", Toronto
C&C 27 Mk IV
There are now two pictures of Legacy's tracks in Black Arts. If anyone has other suggestions, please send them in.
> [The] routine for drilling & filling is elegant & will no doubt ensure a near perfect job.
My method (which I learned from Colin Clark at marine supplier North National) is not just for appearance; you preserve more of the fibreglass layers, which is where your strength is, it ensures that the surrounding balsa and laminate is wetted out, and it gives better assurance that there are no voids or other weak spots, which you can get if you drill all the way through, and then use epoxy so thick it won't run out the bottom hole.
> The explanation & process are without fault, but I do have one question for David. Do you line up the screw heads in a fore-and-aft configuration or prefer side-to-side?
In this instance, I had to use Philips-head screws, which I set at 45 degrees as this arrangement is more tolerant of slight misalignment than others. When it comes to slot screws, thwartships screw-heads are the province of big-endians and other riff-raff. Real men align slot screw-heads to the flow of cosmic power, fore-&-aft.
Incidentally, before I settled on super-sized fender washers, I attempted to use continuous aluminum strip as a backing plate, but the headliner is tacked to the deck with putty, so it's virtually impossible to slide anything in there.
David Weatherston
"Towser", Toronto
C&C 27 Mk IV
Mounting: after many adventures in drilling holes in the deck, backing them up with tape and then filling the hole, only to find that (once again) the epoxy has loosened the tape and run through, I have learned to do the following, which I used to install my own 1" genoa tracks:
- Lay masking tape over the work area, putting a ridge in the lower edge to trap excess epoxy that would otherwise run down the deck. Lay down several lines of it over the track and adjacent area, overlapping like shingles. Rub it down hard.
- With a bit about twice the diameter of the fastener, carefully drill down through the upper deck skin and balsa to just kiss the lower skin, then install a drill stop on the bit and drill everything else to that thickness.
- Dig out as much balsa as can be reached with an awl and vacuum clean. Attach an L-shaped piece of heavy wire to the drill, insert the end in the hole and run. Start with a piece of wire with a short leg on it, then go for a longer one. Vacuum the pulverised balsa out of the cavity.
- Using a syringe (amazing how much hassle this eliminates) fill the hole with unthickened epoxy, then go do something else for an hour or so. Again with syringe, fill the once-again empty hole with cabosil-thickened epoxy. Wipe up any mess carefully (epoxy turns yellow on gelcoat) and go home.
- Come back and drill fastener-sized holes through the middle of your filled hole, right through the deck and where applicable, through the liner. Remove all the masking tape, taking with it all spills, smears, etc.
- From below, drill upward through the liner at the hole locations with a hole saw slightly larger than the largest fender washer you can find for your fasteners. Be super careful to drill only the liner, not the lower skin of the deck. This is a hideously messy job, not to be contemplated if cushions are in. Wear eye protection and a dust mask.
- Dry fit the whole arrangement. Lay masking tape along the track about 1/16 of an inch away. If you plan on covering the holes inside, mark the machine screws for length and cut them (they probably will be the same length).
- Put it all together. I used 3M 5200 as caulk. You need someone on deck to hold the screw head while you fit and tighten the washer and nut. I use nylock nuts; they are reasonably priced if you buy a box from a place like Noah's (see Links & Contacts). It is really helpful to have an electric drill fitted with a socket-holder to speed running up the nuts. Make the nuts snug, not tight.
- Next day, the caulk will have firmed up. With a matte knife or similar, slit the caulk that has squeezed out close to the track, then pull off the tape. Voila, clean deck without endless wiping with solvents. With an assistant holding the screw heads firmly, ensure that all nuts are well set.
- Install all the remaining gear. Install a strip of white plexiglass over the holes drilled in the headliner.
David Weatherston
"Towser", Toronto
C&C 27 Mk IV
We had a lot of leaks in our boat when we first got it, ranging from windows to hoses. This is a trick that helped me locate a maddening leak that regularly put water into the shelves above the settees. Draw a line with water-based marker across any of the suspected water-paths. Examine them carefully after a deck-wetting sail and visit the boat as soon as possible after a heavy downpour. If a line or part of a line has been washed away, you've found a waterpath and if you're really lucky the path may still be wet and will lead you back to its source.
One of our waterpaths had us stymied for a while because it appeared that a tiny amount of water was migrating upward. Obviously there had to be another leak somewhere from which the water flowed downward. Then we realized that in a real blow, when the boat is on its ear, this waterpath _was_ downward and that we had already solved the problem.
As I read your post, I understood it as referring to water between deck and headliner, but Bob England is reading it as being on the sole. We had a problem of water on the sole that turned out to be a minuscule leak in the water system (less than a turn on a hose clamp fixed it). We also had a leak of brownish water into a locker that had me thinking about decomposing balsa. That turned out to be a hose problem, this time with the holding tank. Before you take up Bob's suggestion to taste the water, do yourself a favour and smell the water.
David Weatherston
"Towser", Toronto
C&C 27 Mk IV
Gotcha!
David Weatherston
"Towser", Toronto
C&C 27 Mk IV
The Mk V is a different boat from the earlier 27's but I can't accept your likening of the Mk V to the 24 if you're referring to the one found at your link, which first appeared around '75.
I think you are confusing superficial style with the substantive, where there are huge differences. Everything was relatively beamy (and looked it) in the late seventies/early eighties and a transom-hung rudder is as much a cost-control measure as anything. As such, this rudder is inevitable on a 24-25 ft boat, and by the time the Mk V appeared, essential if C&C were to compete with new market entries. Although there is a family resemblance, the lines of the coachroof differ from one boat to the other and - most importantly - there are vast differences between the hulls and appendages of the earlier 24 and 25 MkII and those of the Mk V.
Both the earlier boats (24 and 25-II) have considerable rocker to their hulls in anticipation of their likely roles as cruiser/racers rather than racer/cruisers. There is even significant immersion of the transom, both qualities likely aimed at giving the boat sufficient volume aft to counter the weight of a crew that expects to sit in the cockpit. Both boats have the slack entry (and probably the fullness forward) of the 27 Mk I -IV.
I remember the Mk V, by contrast, as C&C's response to the rise of MORC and an attempt to recreate the company's reputation for production boats with serious racing potential (an early example was raced by a C&C people associated with the boat's development). It has a flatter run aft with no significant immersion at the transom, probably in anticipation of a crew that would ride the rail or keep to the forward part of the cockpit, thus obviating the need for volume aft. The bow has a distinct knuckle, which usually goes hand in hand with a fine entry, good for windward ability, rotten for carrying all your cruising clobber. For the appendages, C&C discarded the last vestige of the swept-back trailing edge on the keel; the slight rounding at the tips disappeared in favour of the chiselled look that ruled until the advent of the whale-tail style.
All in all, I'd have to say that while you are quite right about the Mk V being a different boat from the 'classic' 27, there's not a lot of DNA shared between the 24, which hit the water around '75, the 25 Mk II, which owed a lot to the 24, and the Mk V, which turned up in '84, eight or nine years later. There are many accusations that can be laid at the C&C Design Group's door, but their willingness to learn and change was never in doubt.
Incidentally, a number of 26's popped up at various times. I vaguely remember a very 25-ish 26 toward the end of the seventies that didn't last long. According to Bob England, who is collecting material on the Mk V for this site, the 26 Wave (later part of the eighties) was a cruising interpretation of the Mk V hull and deck with a larger engine, smaller rig and a winged keel.
David Weatherston
"Towser", Toronto
C&C 27 Mk IV
C&C 27's have a fibreglass headliner inside the structural deck. To work from the inside, you'd have to rip this out. Bad idea in my opinion; costly too. Also, working from inside means that you'd be working up instead of down. Working up with resin and glass is about a gazillion times more difficult and unpleasant than working down. It is also more of a quality challenge.
You may be worried about the final finish but if you work with an experienced glassman who is capable at finishing (and not all are -- get references and check them), your deck will look better than it did going into the project.
David Weatherston
"Towser", Toronto
C&C 27 Mk IV
This is an area that worries me so I checked up on zinc vs. magnesium anodes in fresh water (it worries me because one year I found that my zinc anode was very much chewed up, but a new one the next year was relatively ok, so I assume that there was some stray current corrosion going on, rather than pure galvanic corrosion).
A salesman at Canada Metal said that although they make magnesium anodes for outdrives and saildrives, they only make zinc shaft anodes. He said it was his understanding that magnesium wasn’t necessary on a shaft but “didn’t know the theory”. A mechanic at Eastern Marine in Toronto said that they install magnesium anodes on outdrives because outdrive anodes are in direct contact with aluminum, which is low down the galvanic table. Shaft drives have stainless shafts and bronze or brass props, which are higher up the galvanic table and less vulnerable. Nick Bailey at Bristol Marine says magnesium would be ideal, but magnesium anodes are only made for outdrives, where they will be in contact with aluminum.
I found the table below, which shows that aluminum is near the bottom of the table, magnesium one place lower than zinc. I _assume_ from this difference and the explanation about the relationship between current and corrosion that you want to have as great a difference between the metal being protected and the anode as possible, so on aluminum outdrives you want to go for magnesium. Shafts and props are safely distant from zinc.
Nick closed by saying that the greatest corrosion risk in fresh water is stray current corrosion in which current from the DC system (bad) or AC system (really really bad) is leaking to ground - the water - through your underwater metal, but that’s a topic for another time.
Two last notes on zinc anodes: 1. Fit yours _forward_ of the p-bracket. If your prop shaft ever separates from the engine coupling, the anode will prevent the shaft from shooting out of the boat. A brand-new C&C 62 nearly sank in Lunenburg harbour because it lost its prop shaft. 2. Better quality anodes have a little copper button set in the zinc. When you tighten the zinc down on your shaft, the button squashes against the stainless steel and makes a more reliable electrical contact.
"GALVANIC CORROSION
An accelerated degree of corrosion occurring when two different metals are in contact with moisture, particularly seawater. A metal with a lower position in the galvanic series (see below) will corrode sacrificially rather than one with a higher position, meaning brass, for example, will corrode before gold. The further apart the metals on the chart, the more electric current will flow and the more corrosion will occur. The metals listed at the bottom of the table below will corrode first due to galvanic reaction.
Galvanic Series
Most Protected (Cathodic)
Graphite (carbon)
Mercury & Mercury Paint
Gold
Titanium
Silver
316 Stainless Steel
304 Stainless Steel
Monel
Silicon Bronze
Copper
Red Brass
Aluminium Bronze
Gun Metal & Admiralty Brass
Yellow Brass
Manganese Bronze
Tin
Lead
Cast Iron
Wrought Iron
Mild Steel
Aluminum 2024
Cadmium
Aluminum 1100
Galvanised Iron & Steel
Zinc
Magnesium
Least Protected (Anodic)"
David Weatherston
"Towser", Toronto
C&C 27 Mk IV
Ralph followed up with pictures and text on his replacement. See "Black Arts >> Hyperion's New Engine".
David Weatherston
"Towser", Toronto
C&C 27 Mk IV
In his comments on replacing the A4 on Hyperion, his 1971 Mk I, Ralph Ainslie notes,
"I replaced my tank with one I had made out of stainless steel to original dimensions. When I removed the 30-year-old tank, I could poke my finger through the bottom. Scared the daylights out of me."
Sixty litres of gas sluicing around in the bilge is not a happy thought. Checking your tank, expecially if it's mild steel as Ralph's was, might be a sound idea this spring.
David Weatherston
"Towser", Toronto
C&C 27 Mk IV
Have you thought of going stainless? I like the look of the teak, but every time I see one of my children happily imposing their increasing weight on the gap in a rail, I regret not replacing them when I had them off. I've seen a 27 with stainless rails and they looked good.
I'll second the vote for Noah's if you want to stay wood. Make sure they match the originals. One of the reasons C&C handrails look better than most is because they are not slab-sided -- the bases are wider than the rails, so while being quite beefy, they look delicate.
Noah's will also tell you about a new technique from Gougeon - epoxy-coat your handrails, then varnish for a good-looking and incredibly tough rail.
David Weatherston
"Towser", Toronto
C&C 27 Mk IV
Bruce, I've never seen the point of those little portlights except as a marketing gesture. They are so small and the airflow so negligible (particullarly when screened), they never seem to provide any benefit. (If you want to follow up though, Beckson makes plastic ones made to fit in plexi windows like ours.)
We've had much more luck with a companion drop board with a screen in it and when there's any wind, a scoop on the forehatch (which is also screened).
You might also consider sticking to those blender drinks you mention.
David Weatherston
"Towser", Toronto
C&C 27 Mk IV
Most cored decks have some moisture in them; you need to know if there is too much. What you should look for, therefore, is a credentialled marine surveyor who knows how to use a hammer and a moisture meter, and is capable of making a reasoned judgement about whether the levels found are excessive.
He or she will determine roughly how wet the deck is and the size of the area of wetness. He or she will also be able to determine whether the deck core is sound, or delaminated and/or rotted. From there, he or she should be able to help you decide whether you should pay a figure approximating what the seller wants or the scrap value of the lead keel.
I can't answer your last question without knowing your definition of a 'huge problem'. I saw a 27 whose decks were so delaminated that the stanchions tipped in toward you as you walked the deck. The new owner (who got the boat at a very attractive price) did all the repair work himself and is happy. Other people get pros to do it (which may or may not make sense financially, depending on who you hire). When I bought it, my own boat had highly localized dampness around several fittings in the deck. This I cured by removing the fittings and allowing the areas to dry out over the winter, then sealing the holes' edges with epoxy and rebedding the fittings thoroughly. Five years later, the insurance survey found dampness in the chain plate area. Again, this was quickly sorted out with a few dollops of epoxy. Others have been less lucky. Read "Inboard Tracks for Blade or #3" in this Forum for a description (with costs) of a fairly major deck repair.
Also enter 'balsa' in the Message field of this site's Search function to see several discussions of owner-done or owner-assisted repairs. Run the words 'balsa core delamination' (without the quotes) through Google to see a slew of articles on repairing wet core. That may give you a better sense of what you might be facing. Also, Gougeon Brothers have a $3 booklet called "Fiberglass Boat Repair & Maintenance" that deals with deck repairs with West Epoxy - www.westsystem.com/ .
Moisture in the decks is not by itself a deal-breaker, but it is something to consider seriously. Are you willing to put up with the hassle and is the seller willing to adjust the price? To give a fair basis for answering these questions, you must get yourself a real surveyor (not some goof who 'knows boats') - otherwise you're putting yourself in the perilous position of the man who buys a used car in a dark garage.
David Weatherston
"Towser", Toronto
C&C 27 Mk IV
Here's the disclaimer -- I've heard this described by a fellow I trust, but I've not done it myself (my prop is offset, so replacing the cutless bearing was much easier). According to him, you don't need to remove the rudder, just the prop.
When you disconnect a 27's prop shaft from the coupling on the aft end of the motor, it flops around quite a bit. The degree of 'flop' (or deflection) is usually sufficient to allow the propeller-less shaft to slide past the rudder.
Remembering how much my shaft waved around when disconnected it from the engine when I replaced my cutless bearing, I'm confident that you won't have much trouble. In the unlikely event there is a problem, you can reduce the amount of 'flop' required by dropping the rudder down to the pavement (which means only the shaft will be in the way, not the whole rudder). At that point, you'd only have to deflect the shaft by half the thickness of the rudder shaft (about 7/8") to get it out.
You might be interested in a tool called a Strut-Pro, found at <www.strutpro.com/>, which is supposed to do the job in situations like yours. It looks expensive but if it does the job without a lot of misery, it might be worth its price.
David Weatherston
"Towser", Toronto
C&C 27 Mk IV
> when i stated it was frozen i did not mean temperature-wise
If I had thought you meant iced up, I would have suggested that you just pour hot water on your seacock. It was supposed to be a joke. Oh well, I guess I should hang on to my day job.
It occurs to me that using boiling water is probably a safer way of heating the seacock body than using a heat gun. Water's messy, but a heat gun is hot enough to do real damage if you're not careful. If the water doesn't work, try the heat gun and don't forget the aluminum foil on adjacent areas.
David Weatherston
"Towser", Toronto
C&C 27 Mk IV
I'll restrain myself from suggesting that you wait until it thaws come spring. I assume that you have bronze seacocks as in my Mk IV.
First, try removing the hose and dumping a large quantity of penetrating oil into the top of the seacock. Leave it for a while, then back off the retaining nut a bit and try moving the lever (by hand - don't force it).
If that doesn't work, put in some more penetrating oil and leave it for a week. Repeat above. You might also try easing the retaining nut out until it is flush with the top of the theaded portion of seacock barrel, then tapping gently with a soft-faced hammer on the end of the thread (I suggest backing the nut out and using a soft-faced hammer because bronze is relatively soft and you don't want to damage the threads).
If _that_ doesn't work, put a heat gun on it. Tape aluminum foil to surrounding areas so you won't accidentally melt through your hull or damage the panelling. Warm the seacock body overall until it's really too hot to touch, then try moving the lever and tapping the threaded part (try not to point the gun at the barrel portion -- it's the body you want to expand, not the barrel). Bronze expands readily when heated, and the expansion will almost certainly break the bond between barrel and body.
Use of a heat gun will probably also loosen the plastic part, which is probably bonded in place with some sort of thread compound. The heat may wreck the plastic in the process, but while you are at it, you might as well replace it. The plastic adapters are just standard plumbing fittings that you can find at any large retailer, but you can buy stronger ones made by Forespar from a glass-filled plastic called Marelon.
If none of this works, you may have to pull the fitting, but I've loosened seacocks that seemed permanently welded using the sequence above, and I'm confident that it will work for you.
David Weatherston
"Towser", Toronto
C&C 27 Mk IV
This drawer is a nice idea, but I think you'd want to be careful how much of that 'faceplate' you carve away. If my experience is any indication, it's a compression strut that keeps the two sides of the galley the right distance apart, not just a support for the engine cover.
I removed my 'faceplate' to lift out the engine, then left it out for the winter while the engine was away. After the engine went back (and this was after the boat had been in the water for over a week, regaining its waterborne shape), I found that the icebox and sink were almost an inch closer together, so replacing the piece involved a bit of levering and fiddling. I also noticed that the corners of the 'faceplate' had dug into the ply on either side, top and bottom, which seems to indicate some racking movement.
As I said, the drawer is a good idea that I'd like to pursue but I'm going to err on the side of small opening/thin drawer if I go ahead. Alternatively, I may pursue the idea of a top-opening bin in the engine cover. That's not nearly as convenient, but the cover has no structural function, so you can pretty much do as you like with it.
David Weatherston
"Towser", Toronto
C&C 27 Mk IV
If you google the term 'hull identification number' (aka HIN), you'll get a mass of info on how to read these, including the fairly comprehensive
<http://www.boatsafe.com/nauticalknowhow/hin.html>
which also leads you to information on the manufacturer code at
<http://www.uscgboating.org/recalls/mic_database.htm>,
where the prefix ZOO gives you an Ontario manufacturer of outboard and jon boats. Garbage in, garbage out?
Don't treat this as authoritative, but I believe that C&C used different 3-letter prefixes to differentiate among the several plants it owned through its history (and very early boats would have been made by the separate companies that later joined to create C&C).
David Weatherston
"Towser", Toronto
C&C 27 Mk IV
I've sailed boats with outboards and while an outboard is acceptable for getting in and out of harbour, they're no good for any prolonged use. If there's any wave action, they are constantly being totally immersed or lifted clear of the water (an experience so unpleasant that an inboard was my wife's only inflexible demand when buying our present boat). Given the technical incompetence of your membership, you may find that the repair bills brought on by this characteristic would make you yearn for the days with the A4.
I'd also note that most outboard-powered sailboats have lower transoms than a 27. Fiddling with a recalcitrant outboard (and there is no other kind) while hanging upside down over a 27's transom strikes me as uncomfortable and unsafe -- in fact, downright dangerous.
Someone wrote here a year or so ago that he had replaced his 27's A4 with an outboard. A few of us discussed this on the dock one day and concluded, mostly on the basis of the ideas above, but also on the aesthetics of the thing, that he might have saved a few thousand by going to an outboard, but had reduced the value of the boat by at least double that amount.
As alternatives, consider installing a key switch right beside the raw water seacock and rewiring the engine so it cannot start unless the key is on. It won't guarantee the seacock is open, but it will make the omission an act of such obvious carelessness that you can demand that the villain pays for repairs. A high temperature alarm would be a good idea, too; it wouldn't save the impeller, but it would save the cylinder head (see the Moyer Marine link for an A4 alarm).
Finally, given that this seems to be a long-running problem, it may be time for some policy changes. Rather than throwing out a good engine, have you considered the risk/reward elements in asking people to shut off the intake? Forget about the 'good seaman' aspects of closing valves when you leave a boat. You have to leave the cockpit drains open, so leaving the engine intake open seems a manageable addition to the risk.
Then there is the truly loaded question: have you considered changing the way you qualify people to take the boat out? If a person really is so incompetent that they cannot follow a simple set of rules for starting an engine, he or she probably should not be in charge of a vessel as large as a 27.
David Weatherston
"Towser", Toronto
C&C 27 Mk IV
I replaced my large-diameter head hoses with a recently introduced white plastic hose from Australia called Sealand Technology Odoursafe. (Genco (www.gencomarine.com/) in Toronto sells it and will ship it - probably others have it too [edit - West Marine has it, US spelling]). It isn't cheap but there is now absolutely no odour from my head.
David Weatherston
"Towser", Toronto
C&C 27 Mk IV
I agree with the surveyor that filling the oversized mounting holes with epoxy, redrilling and through-bolting will probably provide the strength you need. As to your liner -- for my genoa tracks, I drilled, filled and redrilled, backing up the nuts with fender washers and covering the holes in the liner with white plexiglass. You are, however, always going to be suspicious of those tracks, so I suggest you heavy it up, if only for your own piece of mind.
As you already are having most of the deck carved up and as you almost certainly will have to have the whole deck painted, why not open the deck in the mounting area, remove the balsa core and drop in a piece of alloy strip that's been drilled and tapped to accept the #3 track? Alternatively, you could glass in the strip, then drill and tap after glassing. Positioning the strip correctly would be fiddly, but then you'd have a super-strong mounting point with a solid glass surround and since the whole thing is done from outside, no holes in your liner.
David Weatherston
"Towser", Toronto
C&C 27 Mk IV
It sounds as if you have a head/holding tank system that follows the Porta-Potti model, in which the holding tank receives an initial charge of water and chemical, and thereafter flushes only with liquid drawn from the holding tank. It's a system that reduces the rate at which the holding tank is filled, but has some obvious disadvantages.
Before you do anything, you should assess the size of your holding tank. The Mk. IV (and presumably the Mk. III) have a 10.4 gal (13.0 U.S.) holding tank. With a fresh-water fitting, this is good only for a few days of cruising with 4 careful users. If your tank is much smaller -- and I gather that many tanks are -- a lake connection may simply fill the tank intolerably quickly, so you may want to stick to the present system, but adopt the practice of rinsing the head post-flush with a small amount of water from the sink.
If you do want to move to a lake-water flush, I'd cap the small-diameter fitting on the holding tank (or better yet, use it to run a second vent hose, which will reduce the growth of odour-causing anerobic bacteria in the tank). Then, connect the intake side of the head pump to your sink drain line, as close as possible to the through-hull. The connection point must be well below the waterline; if it is above or near the waterline, you won't get any water to the head pump.
The virtues of using the sink drain fitting (assuming it works properly) are: you save the bother and expense of a new through-hull; and if you run into the same problem as Aragorn, above, with a smelly head caused by the death of lake-water organisms in the bowl, you can easily rinse the head bowl. Just give the head bowl a rinse post-flush by closing the sink seacock, pumping some water into the sink and down its drain (from which it won't escape, remember, because you closed the seacock), then pumping that water through the bowl.
David Weatherston
"Towser", Toronto
C&C 27 Mk IV
Don't worry about measurements - all the major sailmakers will have lots of data on the 27.
David Weatherston
"Towser", Toronto
C&C 27 Mk IV