On Board with Mark Corke

Zinc time

 

 

Up here in the North East at least, some boats have already been pulled for the season and others will not be far behind. This is just a friendly reminder that one of the chores with the boat out of the water is to change the anodes on the boat. I like to change mine at the end of the season at the same time as I service the engine at the end of the year ready for the coming winter and also it is one less thing to worry about come the next season. Remember that for a zinc to work it needs to make good electrical contact unlike a boat that I looked at recently where the shaft anode was the wrong size for the shaft and someone, presumably the owner had wrapped plastic electrical tape around the shaft to make it larger so the anode would fit!

 

Actually this year I found that my zincs did not get eaten up as much as the previous couple of years. I am not sure why that is but none the less you can see here the difference between the old and the new. No guesses for which is which.

Gel Coat repair

I recently had an e mail from an On Board reader wanting to know a little about gel coat and how to apply it. Gel Coat is basically a polyester resin that is applied to the inside of the mould onto which subsequent layers of fiberglass mat and resin are added to the required thickness thus building up the hull or other fiberglass part. Gel coat is the part that gives the boat or other moulding the nice shiny finish when it is released from the mould.

The clue is in the name gel coat and for it to cure properly it needs to be sealed off from the outside air. Gel coat if applied to a surface and not covered with another material will remain tacky to the touch, but when used as the external surface of a boat will cure as one side is against the mould and the other is covered with fiberglass and thus both surfaces are sealed from the atmosphere. This explains why when doing a gel coat repair to a boats topsides, (nick,dings and scrapes) it is necessary to cover the surface of the freshly applied gel coat with some plastic or tape; saran wrap is a good choice. With the air thus excluded the gel coat will harden under the tape or saran wrap which can then be removed allowing the resultant surface to be sanded, buffed and waxed to match the surrounding original surface.

 

One way around covering the surface to promote curing is to use a waxed gel coat. The wax rises to the surface and excludes the air thus allowing the gel coat to cure. This product is great way for an owner to coat the insides of lockers, under engines and other areas that may be raw fiberglass which would be otherwise hard to clean. The product shown above works a treat for this but you have to be careful not to try and put too much on at once or it will run and sag, also it has to be applied to a clean dry surface and finally if using more than one coat requires wet sanding between coats both to provide some bite and to remove the wax on the surface.  Of course you do not have to use pre waxed gel coat at all you can just buy regular gel coat then before mixing in the catalyst drop in some wax which is stirred in with a suitable stick. The ratio of wax to gel coat should be in the range of 2% by volume but I have found that dripping in a few drops of candle wax from a melted candle is sufficient for a dixie cup full of gel coat and works a treat.

 

Osmotic blisters

If there is one thing that most owners don't want to find when they haul their boat for an inspection it has got to be the dreaded hull blisters. Osmosis is the most often used term for this malady and is caused by water migrating through the outer layer of gel-coat and into, usually, the first layer of laminate which is often the chopped strand mat. Because water is required for the blisters to form blisters above the waterline although possible are rare and as was the case  with this particular boat the topsides looked great and it was only when the boat came out on the hoist that the extent of the damage became evident. The blisters in this particular case ranged from a half inch in diameter up to about one and a half inches, not the worst i have ever seen but bad enough to warrant a major repair.

In a nutshell water migrates through the surface of the hull where it is trapped in small voids that it finds in the laminate. The water then reacts with the styrene and forms an acidic fluid. When the blisters are pictured a smelly brown fluid is released which is the result of the water sitting in the hull for some time. If left unchecked the blisters will grow progressively bigger and permeate deeper into the laminate until the structural integrity of the boat is compromised. We are not at this stage with the boat shown in the picture above but the boat will have to be peeled and the bottom made good, a new barrier coating applied before finally being anti fouled. The cost to repair the damage to this 70 foot motor yacht was estimated at $25,000, not a small sum. If you have a glass fiber boat then be on the look out for blisters each time the boat is hauled and if you spot a problem occurring look into fixing it early. Small blisters can often be filled fairly easily but waiting until things get to this stage is not a good idea. If ever there was a time to use the old adage ' a stitch in time saves nine' then this is it.

Stern packing part 2

I had every intention of slipping down to the boatyard today and grabbing some pictures of me removing and repacking the stern gland on a boat. But that did not happen mostly because I got wrapped up writing a couple of survey reports that the owners were anxiously waiting for so instead I found a very clear and well illustrated piece on the web which does a great job of showing how it's done. I do have a few things to add however and will endeavor to get these posted later this week just as soon as I get a moment to myself

You can see the complete treatment in words and pictures by clicking here

Worn stern gland packing

This short video shows a packing that should have been replaced some time ago. In tomorrows post I'll go through all the stages and show you how to change the flax packing in a traditional stuffing box but in the meantime take a look at this. I was in the engine room when the boat was running at 15 knots and the video shows the packing dripping excessively. If you look closely you can also see that this has been going on for some time by the staining on the inside of the hull which has caused a 'tide mark'.

Cutless Bearings

Changing out the cutless bearing on a boat is one of those jobs that most boat owners approach with dread. You know that it is coming up and you have to do it but you convince yourself that the existing bearing isn't really all that worn and it will do another season. The fact is though that most boat owners with inboard powered boats wait far too long before changing out the bearing. A worn bearing allows the shaft to wobble slightly or a lot depending on the severity of wear resulting in strain on the drive train and engine and a vibration that is hard to ignore..

Now I can't pretend to look forward to this job any more than the next person but as I was cleaning up the prop and replacing the shaft anode I noticed that there was a definite up and down movement that was not there when I performed these very tasks last year.  So the bearing would have to be replaced so I set to it. In the end it was not as bad as it could have been and probably took me a little over and hour from start to finish.

Changing a cutless bearing consists of two distinct but connected tasks, getting the old one out and getting the new one in. Nine times out of ten the best course of action is to remove the shaft. There are all sorts of fancy pullers and so forth on the market that suggest that you can do this without removing the shaft but in my opinion and experience these often do not work, the bearing is corroded into place and no amount of pushing is going to get it to budge.  The easiest kind of bearing to replace is generally a sailboat with a p bracket. After removing the shaft you can get to both ends. Remove the blade from a hacksaw pass it through the hole then reattach it to the saw frame. Very carefully saw through the bearing shell only being careful not to cut into the p bracket itself. The bearing can then be collapsed in on itself  as shown in the picture below.

Once you then reach this point the battle is won and the bearing can be pulled out, often with some vice grips.

On a closed end bearing shell such as those found on a power boat things are a little more complicated. You cannot use the hand held hacksaw as the inboard end of the bearing housing is up against the deadwood or skeg. I have had much success with a sawzall and a fine metal cutting blade but you have to be very careful. Things happen very fast if you do not pay attention and you can cut into the housing easily.

Part two will follow tomorrow and will look at getting the new one into place.

Saving wet electronics

OK so I am sure that I am not the only sailor that has dropped a cell phone in the water from my pocket whilst bending over to tie the boat to the dock.

Assuming that you can get the phone back, I managed it with a kids fishing net attached to a boat hook as the water was not too deep, what do you do next or is a waste of time? 

If the cell phone or other electronic device was dropped in salt water you need to rinse it thoroughly under the faucet, I know this seems like the wrong thing to do but trust me you need to get rid of the salt crystals. Remove the battery if you can as this makes cleaning out the inside easier. Shake off as much of the excess water as you can then pat dry with paper towels. Finally bury the phone or other electronic device in a clean dry bowl of rice and leave over night. The rice will attract and absorb most if not all of the remaining moisture left in the device. With luck the phone or other electronic device will have survived and lived to ring another day.

Even if you manage to dry out the equipment it would be wise to get it to an approved service center asap so they can take it apart and check the inner workings.

Can you hear me now? Installing a VHF radio

Installing a VHF set is one of the best upgrades that you can do to your boat. A lot of boaters think that the use of a VHF set is now obsolete as they will just use their cell phones. This is very misguided as you may be out of cell range and you may not be able to call for help in an emergency. You will also be able to call a marina or another boat even if you don't know their name as most vessels and other radio stations maintain a listening watch on channel 16 which is the International distress and calling channel.

I installed a Uniden 525 similar to the one shown below.

 

You don't need a whole lot of tools but you do need to take your time and be through and precise. In addition to the tools and the actual radio you will also need an antenna and some cable to connect the radio to the power supply. You should follow any instructions that come with the radio with respect to cable sizing and fuses but these are pretty standard across the board. The step by step below should give you a good understanding of what is involved even if it does not match your particular application exactly.

 

1. Start by reading and fully understanding the instructions that come with the radio set. Then make a list of components that you will need which you can gather together before you start so that you will not have to run back and forth to the store once you actually get going.

 

2. Work out the position of the radio set and cable runs and affix the clips to hold the cables neatly out of the way. I have seen so many boats where the owner, in a hurry to get the radio working has just temporarily connected everything up and the wiring is mess. With the clips mounted screw the radio in position. The radio will either be mounted in a bracket, called a trunnion mount or will be flush mounted in a panel, usually close to the helm position.

 

3. Connect the power connection at the back of the radio to the black and red power lead. As shown here this is often a waterproof snap together connector. Starting at the back of the radio and working back towards the power supply enables excess cable to be removed. Avoid curled up excess cabling at the back of the radio at all costs which can lead to eddy currents causing interference to transmissions and mysterious compass deviations.

 

4. Strap down the cables so that they lie flat and neat.

 

5. Cut the cables to the correct length. They should be not too tight nor have too much slack in them, aim for a graceful loop when the wires terminate. The red wire will connect to the fused distribution panel just visible top left and the black to the negative bus bar on the right side.

 

6. Make neat and proper connections using crimped terminals and heat shrink. Never just simply wind a cable around a screw. The connection to the bus bar is a captive ring type while a spade connector was required for making the proper connection to the back of the distribution panel. For more on how to make proper electrical connections you can read my earlier post by clicking here.

7. Ensure that the correct size fuse is used to protect the equipment. A fuse that is too large will fail to blow if a fault develops and either the radio could be fried or a fire could start. The handbook that comes with the radio will tell you what size fuse is required.

8.The final step is to connect up the antenna which nearly always means that you have to put a plug onto the end of the coaxial cable from the antenna. Follow the instructions that come with the plug but ensure that the outer shield wire does not make contact with the central conductor as the plug is assembled. Doing so will seriously degrade the performance of the radio.

9. Screw the antenna plug onto the socket onto the back of the radio. You are now ready to turn the set on and make sure that it works properly. If there is a problem recheck all your connections.

Moving day

I am aware that i have not written much of the hands on and how to content that I like to share of late. The reason being is that I am in the middle of a house move that happens to coincide with the Christmas holidays. I have several boats and a workshop to move from one place to another and when I get to the new house have to set up studio and workshop. This is all going to take a couple of weeks but bear with me, after the move the workshop promises to be bigger and better than that which I have now so all being well I should be better placed to bring you plenty of new and exciting projects.

Worn cutless bearings

I was out in the cold today down at the boat yard taking some pictures for my new book on boat surveying which will be out at the end of next year when I spotted this boat with a very badly worn cutless bearing. It's very short video but if the prop can be wiggled like this when stationary imagine what is going on when the prop is going around at a thousand revolutions per minute! The noise and vibration must be terrible and shake the whole boat. The shaft bearing is completely embedded into the end of the shaft tube which itself is encapsulated within the deadwood and I suspect that the owner knowing it is going to be a pain to remove has put the job off year after year.

Incidentally I found this helpfull on the web link to sailboatowners.com which gives a good idea of what is involved in replacement  of a cutless bearing which you can view by clicking here.