shaft logs

[sevenjohn]

I'm thinking a changing from a wet tank with inside stuffing box and a bronze cutlass bearing to a fiberglass shaft tube. How does the cutlass fit to the log and how is a new cutlass replaced when needed?

 

[El Mar]

I'm sure Captain Larry will chime in, but if you search under his name he put up a great post on the exact subject.

 

[Blitzen]

When you buy your wet tube have them include the bearings fore and aft and make sure the tube is machined for the bearing. Most bearings use set screws on either side of the keel and tube to hold them in place, you can also use adhesive like 5200.

 

[BillD]

When you buy your wet tube have them include the bearings fore and aft and make sure the tube is machined for the bearing. Most bearings use set screws on either side of the keel and tube to hold them in place, you can also use adhesive like 5200.

OK, I'm picturing this in my mind.
On this 33 YB or any other keel boat the installer measures +- the length of the tube required through the keel from well to keel end.

Tube is glassed into place and then end bearings set with allen screws.

From there installer gets exact length of shaft to tranny coupler correct ??

Cutting and glass work and fairing a bit correct?

 

[sevenjohn]

Bill D AND blitzen, that's the idea...i need about an 8 foot shaft tube. Spartan only makes 6 foot lengths....anyone else for tubes?

 

[Blitzen]

Bill it can be done that way but to avoid problems often the shaft, shaft log and bearings all come together so everything is a perfect fit. Also keep in mind that there are tolerances for distance on both ends of the shaft log which should be followed.

 

[tunaorlater]

Call Roses marine. They supplied me with everything I needed. What size shaft do you have? I believe if you look in Hamilton Marie's catalog they show the different tube sizes. Get the biggest tube that your shaft and bearings will fit, this makes upgrading shaft size much easier if ever need be.

 

[sevenjohn]

tuna,
thanks...i just got off the phone with ken at roses...they going to make it .

 

[Sailorgp]

I wouldn't secure a cutlass bearing with 5200...you might never get it out when it's time to replace. I've removed a couple cutlass bearings by first removing the shaft (and engine!!)...then knocking the bearing out with a piece of hardwood that's been cut down to just barely slip inside the stern tube but contact the bearing on it's O.D. and smack the wood with a hammer.

 

[sevenjohn]

Sailor... I believe the cutlass is macined into the tube and installed with a light press. The bearing is locked with 2 stainless set screws on each side.There will be no 5200 involved.

 

[sevenjohn]

Bill D, The engine should be in the hull in a couple of weeks..if we get some reasonable weather..feel free to check it out.

 

[Del]

This winter I am changing from an ancient external bronze stuffing box with integral cutlass bearing to a fiberglass shaft tube, pressed cutlass bearing, and Tides dripless seal. I understand how to bore the slip-fit hole for the shaft tube, and have a plan for achieving precise concentricity tube-to-shaft. But since I have no experience working fiberglass, I need guidance with procedures and materials to build up the area where the shaft tube exits the keel to improve upstream flow to the prop (doing it for aesthetics more than an expectation that a 10 knot cruise will benefit).

I know the shape it needs to be, but I don't want to beef-up the area without hearing how from someone who has done it. Left to my own devices, I would build the surface using thickened West System epoxy with silica filler but not sure if that is the best way or best material.

I don't mean to highjack the thread, but rather hope BillD will gain as well from the advice from the builders here.

 

[Sailorgp]

My 2 cents is that depending upon the amount of material (volume) you'll be laying up, you should plan on using fiberglass cloth in the layup in addition to the silica. The cloth will give it much more strength than the epoxy/silica alone would provide. You could initially use thickened epoxy to eliminate any tight corners where the tube intersects with the hull. Then begin laying up cloth in multiple layers. If the angles of intersection between the tube and hull are difficult, use small strips of cloth or even triangles of cloth to build around the tube overlapping onto the hull. Just remember that cloth will not go around a tight corners. Finally, you can smooth out the joint with more thickened epoxy as needed...then sand and paint.

 

[Del]

My 2 cents is that depending upon the amount of material (volume) you'll be laying up, you should plan on using fiberglass cloth in the layup in addition to the silica. The cloth will give it much more strength than the epoxy/silica alone would provide. You could initially use thickened epoxy to eliminate any tight corners where the tube intersects with the hull. Then begin laying up cloth in multiple layers. If the angles of intersection between the tube and hull are difficult, use small strips of cloth or even triangles of cloth to build around the tube overlapping onto the hull. Just remember that cloth will not go around a tight corners. Finally, you can smooth out the joint with more thickened epoxy as needed...then sand and paint.

Your advice is much appreciated. My new shaft tube will extend about 4 or 5 inches from the keel face in order to replace the support previously provided by the bronze stuffing box. So, quite a lot of material will have to be added. Multiple layers of cloth imbedded in the epoxy is the way I'll go.

Is a product other than West System epoxy preferred for any reason?

 

[BillD]

Bill D, The engine should be in the hull in a couple of weeks..if we get some reasonable weather..feel free to check it out.

Will do !!!!

 

[tunaorlater]

Just curious, why epoxy? The entire boat is poly resin why not use that.

 

[Sailorgp]

epoxy has superior secondary bonding characteristics. In other words it sticks like glue...more so than polyester or even vinylester resin.
When fiberglass/polyester is used to mold a boat hull, the type of polyester resin that's used during the layup operation is the type of resin that doesn't cure completely on the surface....it remains tacky as successive coats are being laid into the mold. The final coat is of polyester is the type that does cure completely. After that, any future polyester that's applied doesn't stick as well as the initial coats. Epoxy is the best way to go for secondary bonding.
I'm sure there are others on this board that can explain it a lot better than I can.

 

[Sailorgp]

Del, West epoxy is certainly a great product. I don't like it because of the 5:1 or 3:1 mix ratio (depending on which hardener you're using). I prefer System Three with it's 2:1 ratio. The System Three Silver Tip resin is a product I swear by. Wets out cloth real well, little or no amine blush and the quick cure flavor works well in cold temperatures.
I installed a bow thruster tube in my Sisu 3 years ago. I laminated it in with many small pieces of 18oz cloth. Over a several day period I built the layup thick enough to withstand a nuclear attack.
I also want to mention that when you're laying up the cloth/resin you DO NOT want any voids, bubbles or resin starved areas in the laminate. Resin starved areas show up as lighter areas in the cloth. You might want to practice laying up cloth/resin on a scrap piece of plywood allowing you to familiarize yourself with the process. It's not rocket science and is an easily learned skill. Finally, work clean and avoid getting epoxy on your skin. It's not very toxic but if you come in contact with it enough you can develop an allergic reaction leading to dermatitis.

 

[Del]

What are the guidelines to use for large volume epoxy-fiberglass lay-ups to avoid overheating the cure? For example, is it best to use 8 lay-ups of 1/4" each to build up a two inch thick area, or what?

 

[F/V First Team]

When fiberglass/polyester is used to mold a boat hull, the type of polyester resin that's used during the layup operation is the type of resin that doesn't cure completely on the surface....it remains tacky as successive coats are being laid into the mold. The final coat is of polyester is the type that does cure completely.

Seriously?

My friend, I do believe you have waxed and non-waxed resins confused with something else entirely.

GP (general purpose) resin (non-waxed) does stay tacky, it's true. This is because it is waiting for the job to be finished, either additional layers or a covering agent such as gelcoat (gelcoat with wax is considered enamel, but it's the same stuff, just has wax in it otherwise it too would be sticky).

Waxed resin has a wax solution mixed with it, and the premise behind this is so that during the cure, the wax will migrate towards the surface with air effectively becoming a covering agent. To get a swell bond with this material abrade it (sand or more preferably grind it).

Two different materials doing similar yet different jobs. Please don't suggest that it doesn't cure completely.