deck construction

A couple of months ago I asked about Decking materials, and received some good info. Well, I have removed the old deck and I am ready for the construction of the new deck and have some final questions.

1) I will be using 1/2 inch marine plywood for the deck. I am planning on using fiberglass on both sides to fully encapsulate the plywood.
Is this a good idea or is it unnecessary to do both sides?
How many layers of fiberglass would make a good deck? I was going to use 18 oz roving and a 2 oz mat overlay.
Would you screw the deck down with stainless screws or just epoxy it (Would the screws give the water a place to penetrate down the road)?

2) The deck was supported by a 2X4 frame of unknown wood (it was black in color). I was planning on using standard 2X4s coated in resin and then fiberglass.
Will this method work, I am assuming that once the 2X4s are encapsulated they will not rot unless water is introduced to them by a hole or other such opening?
Would you use something other than a spruce 2X4?

3) The other question I have is about Hatch openings.
I would like to make them as water resistant as possible. I have seem the new boats with a channel around the inside of the opening to stop the water from entering the interior. I was going to try and replicate this unless their are some better alternatives out their.

Thanks again for your help,
James

 

This is what i am using

Everyone I am getting ready to replace my deck and I am going to use High Density Polyethylene (HDPE). It comes in 1/4 all the way up to 1 1/4 x48x96. The 3/4 I will use cost around $85 which means no having to use resins,expoxys or fiberglass..this stuff will is•less maintenance •machines like wood•will not rot •will not absorb water •dampens vibration •lighter than water, so it floats!•totally recyclable •formable into curved shapes
•sound absorption properties •impact resistant•does not delaminate •environmentally friendly accepts staples for upholstery •high strength to weight ratio

search kelron or codomo using google and you will find it...

 

How are you going to bond the stuff to the floor supports and/or gunwale sides? Isn’t it heavy? At $85 a sheet you could use high grade marine plywood and epoxy. Do you know if resins (epoxy or polyester) and paint will adhere to this? These are honest questions on my part, I am curious how useful it could be. If this stuff is really that good I need be stocking it myself!

Joel
boatbuildercentral.com

 

It's impossible to give an answer without further infos

It's impossible to give an reasonable answer without further infos about the boat itself Size? sail? power? yacht or working boat? material of hull?

 

1) By and large it's not necessary to apply glass to inside BUT do coat inside with 3 layers of epoxy. In some circumstances where heavy duty is a consideration (ie chain lockers) f/glassing interior is in order.
The fibreglass is there to protect the ply, adds very little in terms of stiffness, the thicker the layer the more protection provided.
Most pleasure boats only need l layer of 6-10oz cloth.
I always leave galvanized screws in place, epoxying over them, mostly time saving related. They are countersunk and thus have a pretty good barrier of epoxy over them.
ALL surface applied screw/bolts going into the deck as attachments have potential for rot (over time), drop some epoxy into pilot holes to prevent this. Screws & bolts can be removed for servicing etc by holding heat source onto screw head for 30 secs or so.

2) Standard 2x4s are notoriously knotty due to the quick growth spruce they tend to use. Spruce is not the best wood to use where strength is a consideration.
Check out the difference in price in use a clear Doug Fir of the same depth. I'm assuming (yeah,yeah I know) the old 2x4 was used with the 4" dimension as the deep dimension.
These beams are used to stiffen the deck. The 2" dimension is superfluous over most of the beam.
4x2s are more realistically 3.5"x1.6", you'd be better off using 3.5"x1" Doug Fir beam with a good fillet between this beam & deck (also where beam attaches to rest of boat).

Do yourself a big favour and buy the West System "Wooden Boat Restoration & Repair " & "Fiberglass Boat Repair & Maintenance" costs about $3 each. Great technical advice and guidance.

 

Personally I think you are using way to much cloth and mat. The real reason for 'glassing over a deck surface is abrasion resistance. The amount of material you are planning will add structure, weight and much more effort. Heavy roving and mat aren't needed for a 1/2" deck, unless you wear spikes on deck.

Epoxy alone will not provide much protection. Even tight grained high quality BS 1088 grade plywood will check out in time as the deck flexes with moisture content and driving the boat. You can't avoid either issue in a boat, moisture will find a breach in the coating, fastener hole or joint. The deck will flex and this will cause checking and other issues. Bonding your fasteners and hardware can cut water penetration down a great deal. Most folks don't maintain their craft, making repairs and upgrades as needed, rather then as preventive medicine. A well cared for boat, doesn't leak or have water penetrating it's surfaces.

Reinforcement, set in epoxy will decrease the moisture penetration and stop the checking. Entombing the wood products with epoxy only works if everything is embalmed, not just the new parts freshly attached.

I would leave the underside as a painted surface and use 6 oz. cloth on the deck for abrasion resistance. The deck must be kept painted or UV will have it's way with the epoxy very quickly.

If using Douglas fur plywood, then you will have to 'glass both sides as it will check quite fast, letting in UV and water. Epoxy alone will not stop this. This is much less a problem on different woods where CPES or thinned epoxy may serve.

Typical materials for deck beams would be mahogany, white oak, southern yellow pine, Doug. fur and other dense, tight grained lumber. Typical 2x4 stock is junk and should only be used as staging around a boat on the hard for repair or paint.

This sounds like a trailered boat? If it is, painted surfaces will have a long life, if it's kept on the trailer, covered and ventilation addressed.

Log onto the West System web site and look up the how to do section. You'll get a much better grasp of what you'll need be doing.

Hatches are quite hard to make water tight. Very few builders can make a good hatch. The manufactured hatches are not cheap, but worth the money. They stay tight, look good and are reasonably trouble free. Try to find one in a boat bone yard and replace the gaskets.

 

JR Asked.....How are you going to bond the stuff to the floor supports and/or gunwale sides? Use counter sinked ss screws to attached to the stringers as you would plywood as well. My boat manufactor Sea Arrow used staples. On the edges you apply 3m 5200. I do have a call into Crownline to check on how they apply it as well. Isn’t it heavy? I was told it was lighter then Marine plywood. You would also have to add the additional weight of the sealers/expoxys/fiberglass and all the mess and waiting for it to dry... At $85 a sheet you could use high grade marine plywood and epoxy. I found marine plywood for 80 plus shipping, which was not going to be cheeper when you also factor in the all the resins. I have not checked on the resin or the glass, but to me it is way over the price of this product and then having to spend all the time and energy of sealing it. Do you know if resins (epoxy or polyester) and paint will adhere to this? I was told no on the resins but fusion paint which is for plastic could. I will be applying outdoor carpet on mine so the black color of the sheet will work for me. They do have other colors and tectures...
I have removed the right side of the deck of my 1987 18.5 Sea Arrow open bow runabout with a 200hp gm and mercruser drive just in-case I never mention what I was repairing. It seems they used 1/2 plywood with fiberglass. The foam is in good shap as well as the stringers. I could use 1/2" since the foam fills up each cavity and is even and uniform thank God. The 3/4 is a little overkill I know since I seem to have a well structured hull. I do have pictures that I will work on getting posted....

 

I wouldn’t use stainless steal screws to secure a deck, but that because I would make it part of the boat by glassing it in, not just screwing it on. You can do this as long as the boat does not rely at all on the deck for its strength/stiffness. I dont know enough about your particular boat to say.

I would try to avoid screwing it the stringers as well. You can glue some of HPDE to the sides of the stringer, then screw into that. Good luck.

 

Thanks all for the responses, The deck I am replacing is for a 1976 Century 27 Raven with a hard top. The person that had the boat before me just used regular ply with epoxy and roven material. I am going to try and do it right this time. I have already purchused the plywood ( okame? marine grade 1/2 inch 11 ply) for the deck. The glass is on its way.
Most of the deck is under the hard top with about 5 or 6 ft in the open, this of course was where all the rot was. The guy used 2X4 Pt lumber for the sub structure which seemed to hold up quite well the main problem was that he used regular ply then drilled holes it it for drainage ???????? did not even epoxy the holes.
As far as the hatches go I thought I would just build a box and fiberglass the interior and join it to the deck, I would have a drain in the bottom that would go to the bilge if any water got inside. One was going to be a fish box, one a livewell and the other to hold the batteries, so a little water may be ok. I was going to use fir to go around the engine hatch to keep water out of there.
One more thing, I am planning (unless someone thinks otherwise) to use Sanitread on the entire floor and in the boxes. I know this may be overkill, but I cant imagine I would ever have any water problems after this. I think this would help with traction and help waterproof the livewell and fish box.
Thanks again, James

 

I not all that familiar wit Sanitread, looked it up on Google though. I would say its probably OK for the deck. I woudl just make sure its white or a very light color. If you have a deck made with epoxy and paint it dark, it could get too hot and hurt the epoxy. Best of luck.

Joel
Boatbuildercentral.com

 

To Busted Knuckle:
Sanitread seems to be a non slip coating used on diving boards and such with 'glass surfaces. It sticks to cured 'glass, but does it stick to wood? Are you willing to risk an untested product in this application?

I'd not use a non slip coating in the boxes, as you'll want to clean them out from time to time and the coating will make a much harder job of it. 'glass set in epoxy will provide a nice surface to the inside of bait wells and lockers, without the additional cost and effort of the Sanitread coating.

The decking can use a non slip coating, but the easiest non slip coating is the old tried and true sand and paint method. After you have a few good coats of paint down (cured) scuff the surface with a ScotchBright pad and apply a slightly thicker layer of paint with a brush/roller and before it's dry, cover the floor area with clean sand. Coverage should be so you can't see the paint any more when it's on. When this coat is dry, use a shop vac to remove the sand not stuck in the paint. This leaves you with a 60 grit surface and is a bit much for most folks bare feet, so another light coat to add color and soften the grit. Some folks uses crushed sea shells, walnut shells, ground up bits of car tires, just about anything that can be used in the paint as the "texture" for the non slip aspect.

There are non slip additives you can put in paint, but I've used them and they don't produce even results. There are paints with the anti skid properties included (Sanitread for example) but I've found the old method of adding hard to beat for coats, finish, texture, anti skid properties and cost. A bag of sand from the hardware store cost little.

The Century 27 hardtop is a nice little boat, quite comfortable. The boxes and hatches ideas are a bit unclear to me, but sound okay. You could have gotten MDO at half the cost of that fancy plywood and it would have served as well for you. Before you seal up the bilge area, insure that water can drain to the pumps or transom plug. This may require some "weep" or "limber" holes will need to be drilled to prevent water from being trapped or confined.

To MoneyPit:
DON"T use High Density Polyethylene (StarBoard or similar) as a decking material. HDPE is a NOT a structural product, Doesn't bond to much, though 3M DP9805 will glue it, not in the fashion you require for a 200 HP open boat! None of the manufactures of High Density Polyethylene products will recommend this as a wise use of the product. In fact, they strongly suggest it not be used in this way. This is the wrong product for decking/sole replacement, without a substructure (plywood for example)

The manufacture of your boat used staples for a reason, to hold the ply in place until the 'glass setup. The sole (decking/flooring) is a structural part of the boat and MUST be bonded to the hull sides, stringers, sole supports and generally anywhere it lands or touches. You can still use screws to hold the decking material down, but the 'glass work has to be done, like the factory did it or better then they did. This means re-tabbing the decking material to the boat and 3M 5200 will not cut it on this job, only cloth/mat set in goo will. The plywood is used for bulk and to have a thing to drive screws and other fasteners into when attaching gear/equipment to the sole.

Also, check to see if the foam is holding water, by pricking a small hole in the bottom of the foam blocks/stringers/floatation. If water is seen or you have a vinegar like smell, then you have open cell foam and it will hold water, maybe enough to effect performance.

 

According to their website on of the uses is for boat decks and bilge, I believe it is more for commercial and industrial applications. They make the coating which is smooth when used without the rubber granules. This is what I would coat the livewell and storage areas with, and use the textured stuff for the deck. I actually got the link to the website off one of the threads in this forum. I'm sure you are right about the cost issue. I am trying to make the deck as water tight as possible and was looking for water proof redundancy in the construction of the deck.
I know I am probably putting way to much thought into this, but I have a somewhat obsessive personality which is not a good combination when owning a boat, although I believe the two go hand in hand. Its sure is nice to have a place to bounce ideas off others and get feedback. I appreciate all the info!
Thanks,
James

 

Talked to 3M and they suggest a product DP8010 that will work with HDPE deck board...it is made specifically for HDPE products that will adhere to the HDPE and fiberglass sides of the interior of the boat much like the fiberglass that keeps the plywood attached to the interior of the boat as well.