Propeller Shaft seal foundation

 Propeller shaft seal foundations 

Two years ago when the boat went into the water most of the hull became water tight after some weeks , there was only one issue with the wooden foundations where the bronze unit with shaft seal was mounted onto the bottom of the ship. This foundation on both sides kept dripping water and the only way I could stop it was filling the surrounding of the wooden foundations with Etan grease, which actually hold for almost two years without an issue, boat stayed dry. Since I did not see this as a final repair it was decided to remove them inspect them and if required replace them at the moment the boat would be out of the water for the normal underwater works.

With the knowledge I have from this boat it was expected that the wooden foundations would be fixed with screws through the bottom of the ship. When the boat was out of the water the paint was removed around the propellor shaft where it was expected that the screws would be fitted into the hull.

The next step was to remove the screws, first the plug material for the screw was drilled out with a smaller drill the the actual plug seize one need to be care full not damaging the screw head to much since it will then be difficult to get the screw removed, with a little scraping the hole can be cleaned and the screw easy removed .

 

With all the crews out, shaft and the bronze shaft support removed  I noticed that I would never get the wooden foundations out.

The reason is that it was impossible to remove the foundations since there are two transversal frames  running over the foundations which needed to be removed.

Instead of cutting out the complete frames I removed small sections out of the frames on the forward - and aft side of the foundations.

                                                              forward side

Aft Side 

With these small sections removed, with the use of a multi tool, I was able to get the wooden supports removed from the ships hull. Although this was not as easy as anticipated. I ended up with cutting the caulking between the different sections with a hack saw blade and a wedge between the support and the ships hull, this way slowly separating the pieces from the hull and each other. Unfortunately I lost the pictures of this removal. It is time consuming and one needs not to rush this task otherwise there is a change that the wood of the hull gets damaged, eventually the caulking will get loose from the wood. One important part is to take measurements of the foundation height on different places to the hull before the actual removal is started this since the supports are not 100% straight in lengthwise direction.

                                 Removed foundation grey area is where the water ingress was

When the foundation were removed one could clearly see that it was build up out of two pieces which were hold together with caulking as well as that the bottom piece of the two was fitted with caulking to the ships hull.

The two pieces together also shows that there has been water ingress between them, those are the grey areas on the pictures, caulking just fell off the wood.

                                                          Two pieces on top of each other

One of the reason that the caulking failed could be that the boat has been out of the water for several years and that by drying out of the planks the caulking got loose from the different areas of the hull planks and from each other. Below picture shows areas where the caulking was not attached to the wood.

The parts were cleaned and removed from caulking to be able to take the proper measurements of the wooden pieces as well as further inspection to check if they could be reused.

It is clearly to see from the next picture that the two pieces are shaped under an angle to keep the bronze shaft seal unit horizontal in the boat.

As can be seen from the next picture it was not possible to reuse the removed pieces of foundation some of the wood was deteriorated and had grooves were water would pass through.

The decision was therefore made to make two brand new foundations, instead of using two pieces I planned to make them from one piece. Unfortunately I had not the wood with the right thickness therefore I glued with epoxy two pieces together to get the correct thickness.

Then the part came were the wood needed to be shaped in the right form, first part I used a planing machine .

Then good old manual labor was used to get the pieces under the right angle.

During the shaping of the foundations regular checking was done to see if they are still straight , this is important since if they are not straight/flat they might not fit with the minimum caulking required onto the ships hull.

Before starting with the holes for the propellor shafts the foundations were measured for the correct seize , thickness and sanded to take most of the roughness away.

Next step was to decide where the holes would be positioned in the new foundations for the actual propellor shaft. Center line was drawn on the new foundations and the old one was placed on top of the new one to get an idea of how and where the holes should be made in the new foundations. Blue line is the centerline of the wood and the red line is the approximate oval hole for the propellor shaft. This picture also shows that there were so many holes in the old foundations that it was anyway a good step to replace them.

 

First a hole was drilled in centerline and approximately center for the opening.

Next the hole was made larger with a reciprocating saw, of course following the lines for the expected opening in the foundation. Lines were drawn on the old and new piece to make sure that the depth of the opening for passing the propellor shaft would be the same as original. This was done on both sides of the wood incoming shaft and outgoing shaft of the foundation. 

Then old fashioned hand work started with a chisel to create the opening for the propellor shaft. Important part is to mark the foundations well like port and starboard but also top and bottom this since the openings are not the same at the bottom and top side.

 

Some modern measuring method for checking the depth of the opening.

After the openings are completed on both sides the final thickness of the foundation was completed  and it was checked if all was flat .

All was sanded on both sides and ready to be installed in the boat.

 

Installing in the boat was so called dry installing to see if the propellor shafts would be in the middle of the hole of the foundations as well as that they would not touch the wood. Some adjustments needed to be made to the new foundations, minor sanding .

When al was to my satisfaction the next step was to check if the bronze shaft seal support would be in the correct position. This with the new foundations in place temporarily fixed with a few screws through the hull of the ship. The shaft was temporarily mounted with the coupling onto the engine and it was then checked if the shaft was  approximately the middle of of the bronze unit. At this point the bronze unit was fixed in place with 4 screws. In my opinion it is not useful to spent a lot of time to get the shaft exactly in the middle of the shaft seal since the boat is out of the water and although fixed on quite a few supports under the keel and supports under the hull forward and aft the boat will be different in the water

With the unit in fixed position it was now possible to drill the holes through the foundations and hull for the mounting bolts and nuts. Due to space limitations a long drill was required. The good news is that the new holes in the supports ended up in the old holes of the hull planks.

 

With all prepared for the installation of the foundations the hull and foundations were degreased for final installation. The actual mounting of the foundations was done with caulking for this purpose. I made sure that a thick enough layer was evenly spread out over the fondations to make sure that a 100% seal would be accomplished between the foundation and the hull. The foundations were fixed in place with the screws through the hull from outside. Holes were pre-drilled in the foundations to prevent splitting of the wood.

 

With the foundations in place they caulking on top was sanded off and they were painted. I noticed that antifouling paint will not dry on caulking therefore I used a commercial wood primer , which does dry on caulking, before using antifouling primer and antifouling paint. 

What was noticed at the hull outside was that the holes for the bolts were rather large this was solved by cleaning the holes and installing wooden plugs.

When the glue was cured the holes were drilled through the plugs from the inside and this way I had the exact hole for the bolts I wanted to use. 

Next step was to install the bronze shaft seal units with caulking onto the new foundations.

Bolts were installed with caulking around the thread and at the end the whole bottom was cleaned up and treated with anti fouling primer and normal anti fouling paint. 

On the inside the removed pieces of wood, from the frames, were glued and screwed back in the same position before the boat went into the water.

Looking at the above picture only thing left is to clean the bronze shaft unit which is a nice job for the winter time.,

After the boat was in the water for a few days and after two test runs the alignment of the shafts was checked and as I expected some adjustments needed to be made, but no leakage around the new foundations.