Marine Electronics Forum - Antenna mounting question?

I recently purchased a new Tidewater 230cc and was going to be installing an 8ft Vhf antenna onto the fiberglass T-top. What I'm wondering is there any type of metal plate or anything inside the fiberglass t-top to attach the ratchet mount to? It seems more solid in-between the posts that support the t-top, but I don't want to drill somewhere I shouldn't or where it's not going to securely hold the mount? I got fender washers and was going to thru bolt it through the fiberglass, but in certain spots it seems hollow. Any info would help. I tried emailing Tidewater, but no response yet. Thanks.

You're probably safe going with the fender washers. You're not talking about a tremendous load to the top, so you don't need to torque it down to the point you're pulling the top and the bottom together.

I would definitely epoxy dowels in the bolt mounting holes for the mount if the top is cored or hollow to take up the compression load. if you do not you will crack the gel coat around the mount. and while the load may be small while static, the dynamic load in a sea will be enough to cause some issues....... the fender washers will be sufficient to take up the torsional load and spread the compression load out a bit more.

I would definitely epoxy dowels in the bolt mounting holes for the mount if the top is cored or hollow to take up the compression load. if you do not you will crack the gel coat around the mount. and while the load may be small while static, the dynamic load in a sea will be enough to cause some issues....... the fender washers will be sufficient to take up the torsional load and spread the compression load out a bit more.

What he said

I would definitely epoxy dowels in the bolt mounting holes for the mount if the top is cored or hollow to take up the compression load. if you do not you will crack the gel coat around the mount. and while the load may be small while static, the dynamic load in a sea will be enough to cause some issues....... the fender washers will be sufficient to take up the torsional load and spread the compression load out a bit more.

I think I understand the idea here, but I just want to confirm. Would you take the dowel and drill a hole through the center through which you would pass the mounting bolt? If so, would you need to be concerned about the wood rotting in the future (noob question)? If you would be using the drilled dowel as I have described above, would an epoxied piece of thin diameter PVC pipe peform the same task (compensate for compression load), but limit any risk of the wooden dowel rotting?

Thanks in advance.

Rather than wood dowel, I think drilling a much over-sized hole, filling that hole completely with epoxy, then drilling the actual size hole needed in the center of the epoxy. Unless you're certain there is no balsa coring in the top that could eventually wick water and rot. The PVC substitute for the dowel also sounds like a fine option.

With regards to loading, typical loads for an antenna base will be minimal, but wait until you forget to lower that antenna and hit something overhead at speed. I have actually mounted antenna bases before using nylon bolts with the expectation that they will shear before the T-top gets ripped open...a sacrificial link, essentially.