raising deck

[cantaris]

I am changeing out from an L6 to a chevy 350. I would like to raise the deck to put the motor below deck. I have plenty of interior height. Since the old deck support is on the angled bottom, How do I go about attaching the new supports to the vertical sides? How much space should there be in between the supports? I plan on using 1/2 inch exterior grade ply with resin and at least one layer of glass. Would something like Simpson ties work for attataching 2 x 6 beams to the sides? 3M 5200?

 

[92excel]

Re: raising deck

how high do you plan to raise the deck.. sounds like you will be top heavy which will lead to rollover.

 

[erikgreen]

Re: raising deck

Ditto.

Most boat weight calculations take into account the fact that the deck level is where most of the weight of cargo, people etc. sits.

Raising the deck even a couple of inches can be enough to make a boat very unstable, especially when heavily loaded.

Raising it enough to put a motor below decks would almost certainly cause an accident. Other than that, you'd need to re-work a lot of electrical systems and add ventilation systems to make it legal.

Why do you want the motor below deck?

Erik

 

[cantaris]

Re: raising deck

Guess I was not clear enough. I am completely gutting and restoring/modifying a 24ft 1971 Reinell cabin cruiser. The current deck is 46 inches from the gunwal. I am only going to raise the aft deck which is about 7ft x 7ft cabin to transom. So in my humble opinion I do not think raising a 7 x7 section by what ever amount to clear the v8 is goiing to change much. I will be adding port and starboard 100 gallon fuel tanks under the deck as well as the weight of the engine and cooling system, dual batteries, etc. Wiring will run the way it is now. My question was how to attach the frame work to the vertical hull sides?

 

[Mark42]

Re: raising deck

Sounds interesting. I would love to add my comments, but I can't really picture if from your description.

Can you post some pics or maybe a sketch of what you have in mind?

Thanks!

 

[cantaris]

Re: raising deck

Here is a crude drawing of what I am proposing. The V8 would now be below the deck. This would give more deck space. The back deck is about 7ft wide and about 6-7 ft long. Current height floor to top of gunwall is about 46" I will have to put a higher railing around the back.

 

[cantaris]

Re: raising deck

So! How about this idea. a 2x4 tabbed to the vertical side fore to aft? Then that would support the edge? But what about support for the center? Any ideas?

 

[83mulligan]

Re: raising deck

mine simply have a block tabbed to fore and aft bulkheads. a 2 x 4 runs between the bulkheads and rests in the cutout of the block. the blocks are 3/4" ply. It's held up for 35 years that way. Here is a pic. Edit...those blocks were stapled to the bulkhead as well. I am now a true believer in the holding power of the staple, by the way.

 

[cantaris]

Re: raising deck

If I make bulkheads out of plywood how thick should I use to support the deck? Barring fuel tank area, What spacing should I use between bulkheads? What would be the best method for attaching the deck to the bulkheads?

 

[cantaris]

Re: raising deck

Any ideas?

 

[lowkee]

Re: raising deck

Going on the assumption your current deck is supported by either the stringers directly or existing bulk heads, what is stopping you from simply tabbing 3/4" plywood to each side of the hull for side supports and placing height extensions on the existing deck supports? If you ruff-and-scuff the sides and top of the existing supports, add the extensions on and glass them in place, maybe adding some vertical supports (1x2's glassed in), you will have plenty of support for the deck while using the existing design, just higher.

 

[cantaris]

Re: raising deck

Going on the assumption your current deck is supported by either the stringers directly or existing bulk heads, what is stopping you from simply tabbing 3/4" plywood to each side of the hull for side supports and placing height extensions on the existing deck supports? If you ruff-and-scuff the sides and top of the existing supports, add the extensions on and glass them in place, maybe adding some vertical supports (1x2's glassed in), you will have plenty of support for the deck while using the existing design, just higher.

That's part of the problem. The Reinell I am working on used a couple of 2x6 and 2x 12 non treatedpieces of lumberfor the step down in the cabin, outside the fuel tank and to form the engine bilge. They then put 1/4 inch plywood over that and filled everything with expanding foam. they then glassed over the top. The wood structure under neath was not even attached to the hull. Was tacked to the transom with nails. The deck actually sat on the hull where the "V" goes vertical. Since I removed all of the foam that was apparently support for the deck, I need to make frames and structure to support the new deck. I am hoping to raise the deck up about 12 inches to clear the V8 I am transplanting. sidewall height is not going to be a factor as it comes up to my chest currently.

 

[erikgreen]

Re: raising deck

Okay, just keep in mind what I said about stability. It does matter, even for raising that 7x7 section.

The simplest way (and strongest) that I can think of to attach the deck to the hull sides is with a strong glass joint. Draw out the level of the new deck on the sides using string lines or similar.

Glue a cleat to the hull sides at the level of the line using thickened epoxy as glue. You'll probably want to bevel the side that's meeting the hull to get the top level, but it doesn't need to be perfect. Cleats are basically 1x1 wood poles or similar.

Create supports for the deck across the space.. stringer extensions and frame extensions, so the deck has support every couple feet for 1/2 inch ply and closer for thinner ply. You can space the support a bit farther apart if you glass the deck both sides or use 3/4" ply, or use stiffening beams on the deck bottom.

I'd use cleats on the top edges of the frames and stringers that meet the underside of the deck too. More space for glue to adhere.

Then you put glue on top of the cleats and glue the deck sections down in place. Use more glue to form a fillet between hull side and deck top, and glass the joint using two layers of 6 inch wide tape of 12 oz or heavier glass. No screws needed. Weight the whole deck down until it's cured. Sand bumps down.

Glass the whole deck with a layer of fabric or mat after that. Overlap the tape. Then fill or sand as desired and paint or carpet.

This will give you a one piece deck and hull in that area, which will be a lot stronger than the original deck was, and stronger than just using beams or 2x4 pieces to support a deck span.

Erik

 

[cantaris]

Re: raising deck

Thanks for the run down Erik. I will give it consideration.