Through-bolting dilemma in Catalina 310

[gpd955]

Through-bolting on cabintop
So I had planned on rebedding my dodger frame as instructed by several helpful people on the site. Today, i took advantage of the nice weather and went to the boat to scope out what I thought was going to be a simple project. When I arrived, I was surveying where the bolts would come through and noticed that:

#1. The iterior cabin to is not shaped like the exterior, and
#2. When I tried to use the winch location as a reference I noticed that there are no bolts coming through and that goes for pretty much all of my hardware on top of the cabin.

Figuring that Catalina didn't jsut screw the winches and rigging hardware to the cabintop, I assume that there is a headliner inside and i can't get to the bolts...but then again, how would they expect me to replace/repair things if I can't get to them?? Please tell me my hardware isn't just screwed into the fiberglass.

Has anyone through-bolted anything to their 310 (or other similar style or sized boats) cabintops? Is there a secret way of doing this or am I overlooking the obvious? Any suggestions?

I attached some pics to give you an idea where the frame is mounted.

 

[Steve Dion]

Jack:

I know nothing about the construction on a Catalina, but I can tell you that "Hunter" has medal plates embedded in the cabin structure of their boats. The hardware is drilled and tapped into these plates.

I have never heard of through bolting a dodger but that does no mean that it has not been done.

 

[gpd955]

That's probably the case here.

The frame was screwed in with woods screws and one ripped out because people were using the frame as a handrail. It has been suggested, since there is a decent amounf of force on the frame while underway, that it be throughbolted. I felt that it was the safest and most logical thing to do. Of course, it seems like it is going to be a lot more difficult than I anticipated.

 

[Steve Dion]

Jack:

I do not know if this is practical or not, but maybe someone else can pipe in.

How about drill oversized holes and fill them with epoxy. Then these area can be drilled and tapped so machine screws can be used to secure the screws.

The problem that you will probably have with thru bolting the screws is the interior (area between the coach skin and the interior skin is probably hollow. There would also be issues with the fastener seating on the interior (may not be a flat surface to secure to).

Our dodger is NOT thru bolted and is very secure. If the person that installed the dodger did not drill proper sized holes, this may be the problem.

 

[gpd955]

Jack:
How about drill oversized holes and fill them with epoxy. Then these area can be drilled and tapped so machine screws can be used to secure the screws.

That was the original plan. Unfortunately I may have to go back to that.

The problem that you will probably have with thru bolting the screws is the interior (area between the coach skin and the interior skin is probably hollow. There would also be issues with the fastener seating on the interior (may not be a flat surface to secure to).

It looks like the bolts would come through right on the curve of the interior cabintop. That was a rough estimate but it is really close to that area. And I see where it would be difficult to secure the plate to the mount if there is a hollow space. Kind of defeats the purpose.

 

[RAD]

There is a product that is similar to a toggle bolt that is made of plastic (its like a tywrap) and if your coach roof is hollow then these might work the best, I'll try and find a link for them

 

[gpd955]

Thanks RAD.... That may be an viable "somewhere in the middle" option.

 

[jsalley]

GPD -- All recent Catalinas have heavy gauge aluminum plates embedded in the fiberglass in areas where deck hardware is mounted, and the hardware is bolted to holes tapped in these plates. Unfortunately, there usually isn't any backing where the smaller items like dodger brackets are located.

 

[RAD]

Correction its part plastic, looks like a neat item that would work

http://www.westmarine.com/webapp/wc...toreId=11151&partNumber=543777&cid=2011Annual

 

[ifmdalvey]

To answer your original question, my Pearson 31 is an 1987 model. At every position where hardware has been bolted to the cabin roof, there is a removable fiberglass plate in the cabin lining allowing easy access to the nuts of all fittings. I put a new Spinlock rope clutch on the port side and over drilling the holes and filling with epoxy the fitting was solid and easy. Are there no removable covers in your lining?

 

[NC-C320]

I have a Catalina 320, which is similar to the Catalina 310. These boats, and most made today have an exterior deck and a mating interior ceiling liner. Same with the hull. Catalina puts in metal plates in the fiberglass where things must be fastened securely from the outside. Other places where through bolting is needed there is either wood or solid fiberglass. It is my understanding that things like dodgers and biminis are not typically through bolted on most boats (any brand). As to the liners, if you study how fiberglass construction occurs, you get a smooth side from the mold side. So to have a finished interior on your boat (you wouldn't be happy with the non smooth side), there is a separate molded liner.

Here is a link showing a good bit about how Catalina makes their boats. I think you will find it interesting. http://www.coneys.com/PDF/CatalinaFactory.pdf

 

[rpwillia]

Steve Dion has the idea

Jack, I think most bimini's are screwed in and not through bolted. Sounds like Steve Dion's idea to over drill, fill and tap is the way to go. Although I don't believe our cabin tops are hollow, perhaps you just had a spot that was a little weak.

 

[RAD]

Jack, I think most bimini's are screwed in and not through bolted. Sounds like Steve Dion's idea to over drill, fill and tap is the way to go. Although I don't believe our cabin tops are hollow, perhaps you just had a spot that was a little weak.

One way to find out would be to take a small gauge wire and stick it in the hole with a slight bend on it

 

[wflowe2]

I had a Beneteau which had dodger and bimini. Their hardware was screwed in, not through bolted. I also had to rebed/redril holes occasionally because guests woulg grab the frame when boarding. I currently have a Catalina 320 and the dodger/bimini frame are simply screwed in but because of the wide decks folks don't tend to need the frame for support when getting on and off the boat.

 

[gpd955]

It looks like I'm just going to have to stick with the original plan and fill the old holes and reattach it with the screws. I was hoping for the added support of through bolting but it doesn't look like that will be possible on this model.​

I currently have a Catalina 320 and the dodger/bimini frame are simply screwed in but because of the wide decks folks don't tend to need the frame for support when getting on and off the boat.

I try to keep my "crew" from doing that but no one listens to me. Just like with the house and everything else...if they're not paying for it, they don't care!! Looks like floggings may be in order this summer for those who dare defy the orders of this captain! :naughty:

 

[Sandy Stone]

I prefer to through-bolt anything that might be subject to a heavy strain, for instance a person grabbing the dodger frame for support when the boat took a sudden lurch. You should be able to find round plastic snap-in inserts that cover/fill holes in the interior liner, around 3/4 or 1 inch diameter, big enough to slip a socket wrench through. You would never notice these after the job was completed, however they would be problematic if the hole happened to fall at a curved part of the liner.

 

[Steve Dion]

Technically if the dodger was properly installed, it should not be an issues. We always grap onto the handles when moving about.

The problem may have been some bad glass layup. I would just fill the holes and try again.

 

[Maine Sail]

Technically if the dodger was properly installed, it should not be an issues. We always grap onto the handles when moving about.

The problem may have been some bad glass layup. I would just fill the holes and try again.

Steve,

Many dodgers attach to a flat surface and the force is down. The C-310 dodger attaches to the cabin sides and screws are NOT enough. This was a very, very poor installation choice by JSI. Our failed too potted with epoxy and sold the boat...! Screws are simply not enough in this particular installation. One green water event and that frame is a goner.. Ideally it needs to be through bolted through the cabin sides and into the liner.

The dodger attachment point is right behind the aft port:

 

[Winkfish]

Maybe try drilling in the part you think is hollow from the inside cabin. If it is hollow, cut out a small access hole to see if you can through-bolt it.

 

[Ron20324]

It may depend on how strong your liner is, and there may be a big dollup of epoxy between the liner and deck. I added a number of sheet stoppers and a dodger frame to my B323 cabin top. My dodger mounts are like yours(and about at a 45-degree angle) and they are thru-bolted into the cabins. I took a fender washer and bent it curved to the liner shape and used a locknut, but turned the bolt from outside. It's only tightened down a bit. I see that when people grab the dodger frame, it gives, and the load on the deck fitting does not seem all that much. Most bolts in the cabin have acorn nuts added, but on some I put eye nuts to use for clothes hangers or some dual purpose.