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Thanks Eric, I will check the beveled edge of my portlight to make sure I have enough bonding area with the VHB tape.  I like this idea better than a huge bed of Dowsil 795.

Eric, I've debated using VHB for the next job, which is the aft, starboard portlight.  On the MK II boats this aft unit is partially over the galley and partially in the rear cabin. This means there is a wide fibreglass area under the acrylic where the transition takes place. This will be a big white chunk that's visible using VHB. Is that the same on Mk I boats? If so how did you address that?

Gulf, I didn't take any pics of mine, I was stressing getting the acrylic in place. Noah's photos show the foam tape placement  and the fun cleaning the recess and the aftermath. The Mk II boats don't have screws holding the acrylic, so bracing is necessary.  Getting the bracing right makes things a lot easier, and i didnt do well with that. I was cleaning mine up today and I do have a couple of white spots showing where I didn't get a thick enough bed of 795 in place. Although I do have a continuous seal, so it should be good. Also using the existing portlight you need to mask the inside and outside surfaces. The paper protective layer on new units make cleanup a little easier. 

Alex, I bought Yotache foam weather stripping tape from Amazon. It's 1/2" wide and 1/8" thick and quite dense.  It's self adhesive on one side and it's black so it blends into the sealant.  I cut 3/8" wide pieces and went at it. The basic premise is to allow the sealant a thick enough bed and prevent inward pressure on the acrylic from squishing the sealant completely out.  Remember, the boats aren't made with great precision, so if the portlight material is a bit oversize and the recess a bit undersize the integrity of the seal depends on sealant bed thickness. Don't stress over this job, I did, and it's easier than you are picturing. Bracing and masking/protection are the critical points.  You have approx 15mins to work once the acrylic is positioned in the sealant.

Andy, it's the forward fixed one over the settee by the table, the one with the pointed end.  The wood is slightly discolored, but it's fixable.  The portlight above the stove also has a leak and I will do this one in the spring. The port side portlights are currently not leaking, these are north facing and not subject to quite as aggressive sunlight.

Over the last couple of days I replaced the forward starboard fixed portlight on my 2002 boat.  This is what I learnt and the mistakes I made.
 
The leak has been present, from the forward end of the portlight, for a good while. This meant I could get a sharp, very flexible gasket scraper/putty knife into the sealant, at the leak point and work it gently around the acrylic with some light outward pressure on the acrylic.  The window came out in one piece and was reusable.

The tapered edge of the acrylic looked like someone chewed the chamfer on it rather than routed it.  Secondly, there were no foam spacers between the acrylic and the edge of the recess for the portlight. This results in uneven thickness of sealant. However the boat is 22 years old and probably made 20 years without a leak!

Cleaning the old sealant isn't too bad a job, using a scraper, plastic razor blades, acetone, scotch pad and 180 wet and dry paper. Needs some patience and time. I used plastic drop cloth inside taped around the window to contain the debris.

Basic mistake number 1: I masked the window and the opening, inside and out on one day, ran out off daylight and adjourned until the next day. This caused the tape to be difficult to release.

I used 1/2" x 1/8" self adhesive foam tape cut in 3/8" pieces around the aperture at 6" spacings.  I then applied Dow 795 in a 1/4" zig zag to the aperture flange.  I bought the sealant from a construction supply company in Atlanta for about $11 a tube.

Basic mistake number 2: I should have used more sealant than I did. Really pile it on, you can clean it up later.  You need a good amount around the port after, to allow a consistent fill between the acrylic and the hull.

Dow 795 flies further than birthday cake at a toddlers party.  This stuff goes everywhere.  The good news is it's silicone based, so it's relatively easy to clean up, but plan to cover everything around inside of the boat in the vicinity of the port, as you will be moving quickly, if you are working alone.

I braced the window with ratchet straps and a 2x4 brace with two 4" standoffs from the acrylic.  This standoff is about the maximum that you can get between the inner shroud and the port, as they need to be closer to the ends of the portlight due to the slight curvature, and the only place I could see to attach the ratchet strap was the base of the shroud.  This isn't the best way to do it. Although I did not apply a lot of pressure the acrylic still moved downwards slightly.

Basic mistake number 3: I pulled the tape before I realized that I didn't have a complete bond around the whole width of the flange, (if you don't have a full width seal you can see white around the edge of the portlight).
I applied pressure to squeeze the sealant, and in doing so gave myself a mess to clean up later, around the inner edge of the acrylic. At this point I was not happy with one 4" section of the outer seal, so I applied more sealant.  Unfortunately this section was under the brace and this also gave me some extra cleanup.

I pulled the brace off after a day and a half and the seal is intact, continuous and looks decent before final cleanup, which I will do after the 14 - 21 day full cure time.

In the end, this isn't a difficult job, the masking and the bracing need to be well thought out.  I am not sure any of the bracing ideas I have seen, including CTY cradle with 25LB lead pigs, are completely reliable, and ensure the acrylic doesn't slip. Someone showed suction cups on the inside of the portlight, using line and a truckers hitch to tighten the window.  I think this is a better way, certainly than mine, as you can vary the tension across the acrylic. I might try this on the next one this spring.  If you are replacing the acrylic with new, and they are complete with paper coverings the masking becomes easier and more complete.  The price of 4 new portlights encouraged me to try and remover the old ones first.  If this hadn't worked my next fallback was to buy acrylic and try to cut and rout my own from a paper pattern I made before pulling the old unit.

Pbyrne, that is the standard prop.  Don't try that diameter and pitch with the Campbell Sailor or you will overload the engine.  The shape of the CS blade makes a considerable difference and the 14x8 is the recommended size for Mk II with M35.

Pbyrne, one or two things to remember, if you are installing the prop. You will need to lap the prop taper to the shaft. Use fine valve grinding compound. Get a tube of Engineers Blue apply a very small amount to the shaft to check that the tapers are mating properly. When the tapers are close the prop will stick hard to the shaft and you might need a puller to separate them.  Do not let a boat yard beat your props off with a hammer. This can damage the transmission bearings, never mind other parts.  This is a common practice. My shaft is stainless, which replaced the standard bronze one, which the PO damaged when one wing of his folder stuck! The shaft was butchered to fit the Martec prop. This caused me to have to redrill the shaft to allow the cotter pin to be installed. Be prepared when you remove your prop in case similar issues have occurred.

Noah, I don't disagree with you. The points are purely related to the prop the PO of my boat installed. The Martec I had was about the most basic of its kind.

To be quite honest, I barely motor so my comparison is a bit meaningless.  I will say the Martec was lousy going astern and the CS is a considerable improvement on that.  Theoretically you will lose some speed under sail as the prop just isn't as hydraulically efficient as a folded one, however I consider the improvement in idle setting, the less hammering on the shaft and skeg shift from forward to astern and the improvement getting out of the slip is worth the slight loss in sailing performance.

I have the Campbell Sailer RH14x8 fitted to mine, as recommended by West by North.  Beats the nasty Martec folder hands down.  Mainly as I can raise the idle to a sensible point and stop the vibration at low idle. Talk to West by North before ordering, get the straight scoop from them.  I think mine is slightly over propped as it won't get to 3000rpm.  However, that said, I think my diesel is 10 years old and that is probably contributing more to the lower performance of the engine than the prop. 

I bought one from Walmart, a couple of years ago.  It fits above the stove/ice box on my MkII.  Its about the same height as yours but not as wide, so that needs to be accounted for.  I walked around the microwave section and found the smallest one I could, opened it up and measured it and got lucky.

Do what I do to winterize.  Pull off the intake from the engine cooling through hull and stuff it a bucket of RV anti freeze.  Keep a couple of extra gallons ready with the tops off and chuck them in, if needed to run a bit longer.  I wouldn't run without water or anti freeze running through the raw water side.

A simple question.  How have people cleaned the inside of the stern of the Mk II hull?  Through the aft port and starboard lockers, or by removing the aft water tank and "crawling in", I have zero chance of going through the lockers.

Second point regarding water in bilge.  When there is a heavy storm here I get water in my normally bone dry bilge.  Finally, I think I have found the answer.  The fridge compressor on my Mk II is located in the starboard aft locker, I believe by the factory. In an attempt to duct cool air to the fan they have added a "y" fitting, right above the compressor in the bilge fan exhaust duct (plastic dryer hose).  This Y fitting is open, an I believe in a heavy blow over the stern water gets into the rear of the boat and runs to the bilge.  If you have a similar issue open the starboard aft locker stand on your head and look upwards and you will see the duct, which terminates in the hooded vent on the transom.  See if there are water tracks evident.  This will cause water to puddle in the indentation towards the stern.

If you pull the woodwork from in front of the engine (step mountings etc), it is a lot easier to access the head side on the Mk II boats.  It is still a PITA but a reduction in pain.  It pays to get a mirror in there to look at the hose and oil pressure switch set up to see where the oil is coming from.