170 Rebuild Questions/Advice Needed

[tbergmann93]

Hi all,

I'm in the early stages of rebuilding a 72' 170. I have removed the previous owners attempt at a floor repair, and am down to the cleaned stringer and about 3-4 inches of the old deck on which to lay the new deck. Have a few questions from here on out:

1. For the new deck, planning to fiberglass both sides of some 3/4" marine grade plywood, and then lay it down on top of the stringers and 3-4 inches of old deck. Besides screws, what sort of adhesive should I use to attach the bottom of the new deck to the top of the stringers/edge of the old deck? Just standard epoxy resin that I'll be using for the fiberglass work, or something else?

2. One I get the new floor glued/screw in, I plan to filet the edges into the interior sides, and then fiberglass cloth over that to aid in attachment of the new deck to the interior sides. Is this a good approach?

3. I then plan to coat the new deck in some sort of paint/etc. What (if anything) should be done to the newly fiberglass deck before painting, if anything? Any way to smooth out the texture of the fiberglass cloth or should I just live with it? The end game is to paint the entire interior topsides and deck in the same sort of white coating/paint. What is the best type to use here? I'm not as concerned with it being non-slip as I am with it being a durable, easy to clean coating (I have not been impressed with TotalBoat's topside paints I've used in the past; they get dirty easily and have had some chipping issues.) Open to suggestions here.

4. The exterior topsides I plan to use Alexseal's 501 system with a roller and the roller additive. I've only heard good things about this, but if anyone has any cheaper alternatives that work well, happy to hear.

Thanks!
Tim

4.

[RickK]

Hi Tim, I figured these questions were coming.  They had to because I had the same questions

First thing I would do is make a VERY thorough drawing of the inside of your open hull. You will be so glad you took the time to do this when you need to know things like original floor height, stringer height, width of stringers at the top and bottom for when you need to add reinforcements for seats or tower, etc.  Once you lay in the new floor you can't see these things anymore. Draw locations of everything that is under the floor - In your hull it's going to be primarily the stringers. Also where is the console placed from the inside of the transom and the beginning of the casting deck. You're measuring the original placement.

Lay a 1x2 or 2x2 across the top of gunwale cap and take measurements every foot going forward from the transom. Measure from the bottom of the 1x2 to the top of the stringers. Measure to the top edge (both edges) of the stringers and mark it on the drawing.

Next you measure from the starboard inside of the hull or liner and measure, moving toward the port side, to the bottom of the closest stringer and also the closest top edge and then repeat with the other edge on the port side of the stringer. Then go to the next stringer and repeat. Repeat taking measurement every foot for all the stringers going forward.

One thing the drawing does for you is save you climbing into the boat every time to measure something - you'll already have the measurements. Years from now you'll still have the measurements in case you want to add something. I still have mine.

3/4" will be stout for sure for the flooring, maybe too stout once you add 4 layers of cloth. I used 3/4" for my transom but used 1/2" composite for the floor.
I used thickened epoxy to glue the floor down with about 10 cinder blocks for weight. You mix it up and pour into a gallon zip lock bag. Cut the corner off and squeeze in a "S" all the way along the surfaces that will connect to the underside of the floor.

[tbergmann93]

Thanks Rick!

Great advice I will definitely take note of.

In regard to paint/gelcoat over the new deck and on the interior sides of the boat, what is your recommendation? Looking for something that I won't have to redo every few years if possible.

[RickK]

On mine I rolled gelcoat and sprinkled glass bead over it, then lightly coated it with gelcoat again. It's durable and easy to clean. I made sure that I used polyester resin on the top side of the floor because I knew I wanted to use gelcoat.  If you're going to use epoxy, you'll probably want to use good quality paint.

[tbergmann93]

Thanks Rick!

Do you mind going into detail on what you mean here: "when you need to add reinforcements for seats or tower, etc". What sort of reinforcement is needed under the seats: is the new 3/4" plywood over stringers and glass not enough 'beef' to hold the new seats with screws?

If not, is the solution adding another level of raised plywood over the main deck, or something else entirely?

Thanks for the help,
Tim

[RickK]

The demise of any floor is the improper sealing of any screws that penetrate the wood. Once water gets into the wood it starts to rot, doesn't matter how thick the wood is to start with. The best way to penetrate the wood and protect it is to overdrill the hole (drill a hole bigger than what the screw needs) and then fill the hole with thickened resin. Then you pre-drill the hole into the resin for the screw size being used and when you insert the screw, it is not touching any wood, just resin.

If you have the typical cooler seat you don't need much to secure it but still need to protect the wood. If you have a leaning post, you treat the wood the same way but will need more mounting points. The best way to secure things to the floor is to pre-drill holes as mentioned above and use threaded inserts and bolts.
I had a custom seat made for my boat and I mounted it using threaded inserts (T-nuts) for 1/4"x20 bolts.




I marked the holes in the seat base and over drilled/filled the holes




In the end I found 1/4-20 bolts with tapered heads and mounted the seat using the inside bolt holes only.