Autopilot shelf

[felizcortez]

I am installing a B&G T2 Ram with a NAC 3 controller. I spoke with a few people at the boat yard here and am making a few improvements to the shelf.

1. The side and front are getting a second piece of ply to double the thickness.
2. I am adding 2 large pieces of bar stock under the top of the shelf and will glass those in. They will run all the way from the front to the hull.

This should significantly beef up the shelf and also provide greater contact area with the hull helping spread the load more. This should end up being significantly over built.

This will all be epoxied and glassed together. I'm finishing up fabrication tomorrow then will start glassing. I ground off all the paint and left about 5 inches around the shelf to accept tabbing/glass

I was going to cut a bunch of 4 or 5 inch strips to do all the tabbing and match co tours.

[felizcortez]

I glued the shelf together using 404 high density filler today. I'm going to wait for that to dry then make sure it fits then start glassing tomorrow.

Before I tab it to the hull I was going to put thickened epoxy on the contact points to get a good adhesion/contact patch and fill any gaps. Should I use the 404 high density filler or 406 colloidal silica? Or doesn't it matter?

I was going to do the bottom first then apply it to the hull tabbing in the bottom side. Then work around the outside tabbing it in. Then eventually cover the top. Are 4-5 inch strips sufficient? And just overlap them? I am working in a locker In a tight space so I'm trying to think through this stuff ahead of time.

[stormalong]

That shelf looks way better than the original. If you are doing four layers of wide tabbing I doubt that any filler between the shelf and the hull matters but it couldn't hurt. Maybe a little wider on the tabbing where it is glassed to the plywood. If your strips are 5 inches wide that is only about 2.5 inches on the plywood. After it is all cured a few screws through the glass into the plywood may be a good idea. That may be overkill but I like overkill.

Good on you for discussing the design with other boat people.

[coopec43]

Internal relief valves protect the unit and its mountings from rudder strikes, grounding etc.


PERFORMANCE

..........Hard over time........................ Typical max thrust
......seconds at 5 kg....................................... kg

RAM T1............... 13 .................................... 700

RAM T2 .............. 9 ..................................... 700

[felizcortez]

I'm having trouble figuring out how to pattern the fiberglass. Should I just use strips? And then overlap them as I go since I am in a confined space? Does it make sense to tab it in with parallel strips to the shelf or should I just run them perpendicular and work my way across? Or should I go for one big piece of cloth to try to get it from top to bottom?

[stormalong]

Originally Posted by felizcortez

I'm having trouble figuring out how to pattern the fiberglass. Should I just use strips? And then overlap them as I go since I am in a confined space? Does it make sense to tab it in with parallel strips to the shelf or should I just run them perpendicular and work my way across? Or should I go for one big piece of cloth to try to get it from top to bottom?

Once you have the shelf glued into place just start with narrow strips lengthwise along the joint and widen them as you add more layers. The length of the strip can be as long as you are comfortable handling. I would start with 5 inches wide and add two inches of width for each layer. That way each layer is bonded to both the previous layer and the original surface.

Have you laminated 'glass before? Start by painting a layer of epoxy on the surfaces on the shelf and hull. Then wet out a strip of fiberglass on a plastic sheet. Pick up the strip of fiberglass and lay it in place. Use a fiberglass laminating roller to squeeze out any bubbles and to make sure the cloth is solidly against the surface. Do as many strips as necessary to complete the layer. Then repeat the process with the next wider strips. Don't do more that four layers at a time - probably all you will need. Too many layers will build up heat and you do not want the layup to get too hot. Also mix the epoxy in small batches for the same reason. I once had to throw a batch of epoxy on the ground because of how hot it got - I thought it would catch fire. Use the slowest hardener that conditions will allow, again for the same reason. If you stop the layup process for more that about 24 hours you will have to sand or grind the new work to get rid of the blush. Best practice is to start early in the day and do it all in one day.

You will want to wear throw away clothes or a tyvek suit. Nitrile gloves are essential. I usually save old clothes for epoxy work and bottom painting.

There are a lot of youtube videos on laminating fiberglass.

A big advantage of epoxy over polyester resin is longer potlife and work time. Use that to your advantage and take your time.

[DeepFrz]

Originally Posted by stormalong

... If you stop the layup process for more that about 24 hours you will have to sand or grind the new work to get rid of the blush. Best practice is to start early in the day and do it all in one day.

You will want to wear throw away clothes or a tyvek suit. Nitrile gloves are essential. I usually save old clothes for epoxy work and bottom painting.

There are a lot of youtube videos on laminating fiberglass.

A big advantage of epoxy over polyester resin is longer potlife and work time. Use that to your advantage and take your time.

Don't sand or grind the amine blush. You wash it off with soap and water, then you can sand to produce a tooth for the next layer, if necessary.

[felizcortez]

Originally Posted by stormalong

Once you have the shelf glued into place just start with narrow strips lengthwise along the joint and widen them as you add more layers. The length of the strip can be as long as you are comfortable handling. I would start with 5 inches wide and add two inches of width for each layer. That way each layer is bonded to both the previous layer and the original surface.

Have you laminated 'glass before? Start by painting a layer of epoxy on the surfaces on the shelf and hull. Then wet out a strip of fiberglass on a plastic sheet. Pick up the strip of fiberglass and lay it in place. Use a fiberglass laminating roller to squeeze out any bubbles and to make sure the cloth is solidly against the surface. Do as many strips as necessary to complete the layer. Then repeat the process with the next wider strips. Don't do more that four layers at a time - probably all you will need. Too many layers will build up heat and you do not want the layup to get too hot. Also mix the epoxy in small batches for the same reason. I once had to throw a batch of epoxy on the ground because of how hot it got - I thought it would catch fire. Use the slowest hardener that conditions will allow, again for the same reason. If you stop the layup process for more that about 24 hours you will have to sand or grind the new work to get rid of the blush. Best practice is to start early in the day and do it all in one day.

You will want to wear throw away clothes or a tyvek suit. Nitrile gloves are essential. I usually save old clothes for epoxy work and bottom painting.

There are a lot of youtube videos on laminating fiberglass.

A big advantage of epoxy over polyester resin is longer potlife and work time. Use that to your advantage and take your time.

Ok. I understand the tabbing part, but after I do that and tab it in, I still need to cover the rest of the shelf. Do I just go to the tabbing as well there and do 3 or 4 layers using strips in a different direction?

[stormalong]

Originally Posted by felizcortez

Ok. I understand the tabbing part, but after I do that and tab it in, I still need to cover the rest of the shelf. Do I just go to the tabbing as well there and do 3 or 4 layers using strips in a different direction?

You should always overlap the tabbing for strength. If you are using conventional cloth I would not be concerned about the direction of the weave. If you are using something more unidirectional just crisscross the layers.

I think you have the strength issues covered and will be fine either way.

In my first response I told you that I did this mount in 1990 and it is still good. Back in those days I was new to fiberglass work and the cloth was just cloth. In the years since when I have done glass work I have alternated layers of cloth and mat. I have seen youtubers do just cloth and cloth and mat. I am not a pro, I have sealed up unused through hull holes, some below and some above the waterline. I have also tabbed in previously thru bolted brackets and laid up a separate sump the take chain locker sea water. I am happy to say that I have never had to redo these projects.

What I am trying to say is that in my opinion you have it covered and you shouldn't worry about it. The double layer of plywood and the tabbing have give you the strength that you need. Covering the entire shelf with fiberglass gives you additional structural integrity and means that bracket should last just about forever.

[felizcortez]

Originally Posted by stormalong

You should always overlap the tabbing for strength. If you are using conventional cloth I would not be concerned about the direction of the weave. If you are using something more unidirectional just crisscross the layers.

I think you have the strength issues covered and will be fine either way.

In my first response I told you that I did this mount in 1990 and it is still good. Back in those days I was new to fiberglass work and the cloth was just cloth. In the years since when I have done glass work I have alternated layers of cloth and mat. I have seen youtubers do just cloth and cloth and mat. I am not a pro, I have sealed up unused through hull holes, some below and some above the waterline. I have also tabbed in previously thru bolted brackets and laid up a separate sump the take chain locker sea water. I am happy to say that I have never had to redo these projects.

What I am trying to say is that in my opinion you have it covered and you shouldn't worry about it. The double layer of plywood and the tabbing have give you the strength that you need. Covering the entire shelf with fiberglass gives you additional structural integrity and means that bracket should last just about forever.

I glassed in the shelf today. Not super pretty, but got the job done. I ran out of resin about half way through the job which was a stupid rookie mistake. It is hard to get the stuff in Mexico and I ran over to the boat yard and bought some more off another cruiser. They saved my bacon today along with preventing a ton more work.

My wife made up strips of glass while I was in the locker and handed them to me. I think we got pretty good coverage all around especially on the tabbing. I need to sand a few areas tomorrow after it fully hardens to knock down some sharp fibers that are sticking out.

Now the fun part starts of finishing up the rest of the installation.

A few lessons learned.

1. Two people makes a huge difference. Having someone else wetting out cloth and handing them to you makes thing much easier. This would be very difficult to do solo in a locker.

2. I tried using a roller, but found my hands were much better at smoothing the cloth. It would pull away from the filets when I was trying to spread it and so I constantly needed to readjust it.

3. Make sure you have enough resin and hardener. I wasn't sure how much we would use, but this one should be self explanatory.

4. Smaller pieces were easier to work with and get smoothed out. Especially in tight spaces.

5. You will use more cups, brushes, gloves, squeeges, etc than you believe you will. We went through a ton on this project.

6. Try to do the wetting out of the glass out of direct sunlight. I could feel the pieces done down noticeably warm.

7. Lay down more plastic than you think you will need. Epoxy will get everywhere and you are going to make a mess.

8. The pumps are vital. I wouldn't do a job without them now. It makes measuring idiot proof and faster.

9. Clean your tools quickly after finishing with acetone or any time they get sticky due to the epoxy starting to set.

10. Try to cut a bunch of smaller strips before you start. This makes things to faster.

This was a lot more work than I thought it would be. I realized when I was making the shelf, I was going for too much precision. I am not building a watch and thickened epoxy fills decent sized gaps the main priority is strength. Once I got a little more rough with things they went much faster.

[stormalong]

Well done. A little sanding or grinding on the rough edges and you're done. Wait for the epoxy to cure hard before sanding.

[Matt Johnson]

Thanks for posting the follow-up.

Judging by the one photo, but you may be a little dry in a few spots on the hull tabing. Once it has cured, take a screwdriver and hold it by the metal end... tap the handle along the glass work and you can hear if there are any voids.


Matt

[felizcortez]

Here is the autopilot install completed. Things are working great after the installation. It's like having an extra crew member on board. Still need to paint the glassed surfaces, but things are all installed.