REMOVAL OF PROP SHAFT

Today I removed the prop shaft for a few reasons. First, I decided it would be easier to remove the gelcoat around the area of the shaft and strut with it removed. Second, the strut attachment is a bit loose and the attachment needs to be reworked. And third, the strut bearing could use to be replaced as it has a slight bit of play in it.

The shaft is held to the transmission by a coupling attached to the prop shaft. There are two set screws and a key way that hold the coupling to the shaft.
To start off with, I loosened the stuffing box adjustment nut so that the shaft could be moved around a bit more easily. I then loosened the set screws, which came loose without too much difficulty. The bolts holding the coupling to the transmission were a bit more difficult. With a bit of penetrating oil, a bit of waiting time, and some muscle, the bolts came loose. Once the bolts were removed, the coupling came loose from the transmission without any difficulty.

Once the bolts were removed and the coupling free from the transmission, I attempted to remove the coupling from the prop shaft. As it turned out, the two were slightly corroded together and did not want to separate from each other. I first placed a spacer between the prop shaft and the transmission output. Then I reconnected the prop shaft coupling to the transmission and tightened the two together with their attachment bolts. Here is a picture with one of the spacers in place.
I had to use varying sizes of spacers as too long of a spacer would not allow for attachment of the coupler to transmission bolts. The spacer in the above picture is a socket that is just slightly smaller than the diameter of the prop shaft.

Once the coupling and prop shaft were detached from each other, the remainder of the removal was quite simple. The prop shaft simply slid out of the boat and strut.

A few additional pictures of the process follow.

GELCOAT REMOVAL EXPERIMENT

I've begun to experiment with gelcoat removal techniques. As I had previously mentioned, sandblasting does not appear to be a good alternative as the blasting easily damages the fiberglass underneath the gelcoat layer. I've been experimenting with alternate techniques and believe I have found a decent option.

I first attempted sanding with an air file using 36 grit sandpaper. This worked but took a considerable amount of time and effort. I liked the surface left by the air file, but needed to find a quicker and easier way to take down the gelcoat.

I next experimented with using a 5" pneumatic rotary sanding disc, using both 36 grit and 50 grit sandpaper. Both sandpaper options took the gelcoat down very quickly but left a somewhat flattened surface.

I experimented a bit more using the rotary sanding disc to remove a majority of the gelcoat and then finished off the surface using the air file. This seems to be working relatively well. The rotary disc takes the gelcoat off very quickly and the air file leaves a relatively fair surface.

The tools used were purchased at Home Depot (rotary sanding disc) and Northern Hydraulics (air file). They are probably not the highest of quality but are accomplishing the job and were reasonably priced. Both came with a long enough warranty to cover replacement should they burn out during the course of the work.


Once the gelcoat was removed, the voids in the fiberglass where the blisters were occuring were quite visible.



I'm currently doing some research on moisture meters as I'd like to identify any major problem areas if they exist. More on moisture meters to follow in a later posting...

The job of removing the gelcoat is going to be quite time consuming. Depending on the amount of time I am able to commit, I'm guessing the removal process will take the better part of the next few weeks. I think there may be another option for removal that may be a quicker solution, but the surface I'm achieving with the method described here is leaving me with a relatively decent surface. I'm hoping that more time spent now will mean less time spent later fairing out the finish surface.

More to come as work progresses...

BLISTER REPAIR

Upon removing Hullabaloo from the water for the 1st season, I discovered a rash of blistering. With too many projects already on the list for the 2008 winter season, I quickly decided to temporarily ignore the problem and deal with it the following winter season. Well, we're now here and it's time to tackle the problem.

Hullabaloo came out of the water on October 13 and made its way into storage. Knowing I was planning on taking on the blistering this season, I decided to go with indoor storage so that work could occur over the winter months. Luckily I was able to get inside. Pier Milwaukee is limited on indoor storage, but they managed to squeeze me in.

The boat is tented in within the building and I installed a simple exhaust system to keep the dust out of the rest of the building for the duration of the work.

After doing some research, I decided to remove the bottom paint and gelcoat using a sandblasting process. The bottom paint is VC-17. After beginning the process, I discovered that there was also an older paint system below the VC-17, but I do not know what the paint system is. It does not appear as though there was ever a barrier coat applied, so I obviously did not need to worry about removing a barrier coat system.

The blasting media that I have used is Starblast. West Systems recommends Black Beauty but after talking with a local contractor who has done this type of work, they felt Black Beauty was a relatively aggressive media for this application. They recommended Starblast. The other item that I found in doing research on the type of media is that you do not want to select a media that will fracture upon hitting the blasting surface as the fractures can become embedded into your final product.

The VC-17 paint came off almost effortlessly. The bottom paint below the VC-17 took a bit more effort to remove. I figured out towards the end of the process that it is important to have a fresh nozzle in the sandblaster. The nozzle I was using was worn. I replaced the nozzle with a new 5/32 nozzle towards the end of the paint removal process and was surprised at the difference it made.

Once the bottom paint was removed, it was on to the gelcoat. There are basically two options for opening up the blisters. When there are a manageable amount of blisters, they can be individually drilled out using a countersink bit. In my case, there were literally thousands of blisters over the entire hull. This meant either countless hours of grinding each blister out (and hoping I did not miss any) or removing the entire gelcoat to open up the blisters. I have chosen the option of removing the entire gelcoat below the waterline.

My initial thought was to sandblast the gelcoat off. I realized quickly that this is not as easy as it sounds. The gelcoat is a rather dense material whereas the fiberglass below the gelcoat is much softer. The gelcoat takes a considerable amount of time to sandblast through and, once through, it is almost impossible to not gouge into the fiberglass layer, leaving an extremely rough surface.

I've disussed options with a few guys at the yard for removing the gelcoat. Most everyone seems to agree that sanding is probably the best option. I've decided to use a pneumatic board sander. I experimented a bit tonight using 80 grit paper. It seems to take quite a bit of time to work throught the gelcoat with this grit. I'm going to attempt tomorrow to us a 36 grit to get through the majority of the gelcoat and then finish off with an 80 grit. More to follow after tomorrow....