37 minutes ago, Jordan22 said:

I feel like that washer is going to be very important to so that the nuts don't just slip right through the hole of the wood once it softens and experiences a bit of rot.

By the way, it seems to me that the washer and nut will always be against metal, not wood.  Why does your photo show a washer against wood?

Countersink the top where the carriage head goes.  Hit it with a hammer and punch to seat it.  Jam a screwdriver in the hole against the head if you need more tension.

On the other side, use a washer and nylock nut.  Don't use the regular nuts except if you need to pull the bolt heads deeper first.  They won't make the bolt heads spin like the nylock will, but you don't need them on the final product.

As @Nick55 said, an impact wrench will allow you to just do the job without the hammer or extra tools.

The Rock river in Rockford. Lots of glass.

Here is a photo of an Indmar LS3 in a 2013 Supra and a photo of an LS3 crate engine.  It looks like the same fitting has a plug covering the vacuum inlet in the photo.  My understanding is the fitting is usually connected to the power brake booster in an automotive application. 

I don’t have much to add here other than to say: the 2022+ 25 LSV is the most well rounded family boat in the lineup, imho.

I had a 2022 but “upgraded” to a 26 LSV last year… didn’t like it, now back to 25…