Quickie hard top project

[erikgreen]

EDIT: Sorry about the loading speed of the pics here... I'm hosting them on my home server as usual, and my internet line can get overloaded. Patience is a virtue



I've been doing a lot of boat stuff lately, diving with my usual group and getting my 21 footer ready for use. I had dropped off my level of boat building projects to have some spare time.

But getting my Sea Ray ready made me feel like it was a broken down old boat. It's in better mechanical shape than when I got it (reman engine with about 100 hours on it) but it looks like it's been dropped off a trailer onto a highway (which it has).

So I felt like sprucing it up, removing the bad flooring job I did last year, doing some painting, etc. I made a list, then sighed a big sigh at how long it was.

Most important was getting the lower unit skeg fixed, since I couldn't steer straight at low speeds (kinda necessary for running a towed sonar). I also need a davit for handling the sonar cable.

But the thing I wanted most after those was a better way to mount my antennas, a place to mount some lights, and a top to keep me out of the sun... cruising back and forth for hours is well and good, but I look old enough as-is, so I wanted shade.

So, after spending time learning a lot of good techniques working on my scratch-build project, I decided a hard top is in order.

I'll be posting pics later tonight or tomorrow, but for now here's a pic of the boat as is:

Well, this is actually before the accident, so I've re-done parts of the trailer (new axles, new brakes, better bow stop) and the hull looks a bit rougher (dings, etc).

But in general, here's what I'm going for with the hard top:

Okay, probably a bit taller than that. Plus the legs will be re-designed as needed for rigidity. But you get the idea.

I'm going to use a plywood core covered with fiberglass, using scrap wood from my scratchbuild project. The support legs will be 1 inch aluminum tubing that I have from a while back plus some scrap aluminum I got from my neighbor cleaning out his garage.

I've gotten about halfway done on the top at this point and I'm starting the legs, so I should have a story to tell soon.

Erik

 

[jonesg]

Re: Quickie hard top project

It would look better if the side glass wasn't angled.
I like the penn yan hardtops I see for sale.
Are you gonna do side walls or leave it open?

I found some fibreboard at home depot, white on one side, brown on the other, I thought it would make a good surface for a layup table for my T-top roof, then I discovered its actually waterproof, I left it out in the rain and its perfect, then I actually noticed the label says its for shower walls.doh!

So now I have a pre-painted roof already finished, I'll core it with urethane sheet insulation foam and, mat and resin.

Just an idea if you wanted to save weight over plywood....
unless you plan on walking on it.

 

[erikgreen]

Re: Quickie hard top project

Well, I'm using high quality 5 layer 1/4" ply, so it's not much weight. Covered in glass it should be capable of holding me, although that's not something I'll do very often.

I've been playing with the idea of removing the windshield entirely once the hard top is on, and replacing it with removable canvas/plastic panels, like a camper top. It would save a ton of weight plus make the boat able to fit in my garage in the winter.

Or I could replace the windshield with an air deflector on the drivers' side. Dunno yet, I'll have to see when the top's on it.

Erik

 

[drew2302]

Re: Quickie hard top project

Looking forward to the pics when you're finished ,

 

[dingbat]

Re: Quickie hard top project

1" diameter aluminum tubing isn't anywhere near strong enough for a hardtop. The uprights on mine are 2 1/4" diameter

 

[erikgreen]

Re: Quickie hard top project

Well, it's only "tubing" in the outside dimensional sense.

It's actually thickwall tubing, 1/8" wall and 3/4" interior diameter. I agree that 1 inch isn't my preference for hard top support either, but it's what I have.

My final test for useability will be putting a large amount of weight on the top and legs before mounting, so I guess we'll see at that point.

Erik

 

[Bondo]

Re: Quickie hard top project

I agree that 1 inch isn't my preference for hard top support either, but it's what I have.

Ayuh,... Twin 'em, ladder-bar it, gussets,... Whatever it Takes...

I don't think it'll Fly as pictured above....

You guys have got Me thinkin' about maybe using This Stuff,...
To cover the Top in the works,+ possibly recovering the Top on the starcraft...

The starcraft Top is covered with surplus Nato refuge Tent material...
I have it Battleship Grey outside,+ Olive Drab inside....
6 years,+ No signs of Failure,... Yet,....Wish I could buy more of it..

 

[erikgreen]

Re: Quickie hard top project

I and a friend used some of that FRP from Menards to re-cover the back cabin wall (outside) on his 30 foot trojan. It's similar to the StructoDecor stuff in that link.

2 years later it hasn't faded at all.. he's not happy with it because he's kind of a purist about the whole thing

But it lasts and lasts. Nice stuff if you want a weather resistant surface.

I'd give it a try but I'm just going to paint mine.

Erik

 

[jonesg]

Re: Quickie hard top project

1" diameter aluminum tubing isn't anywhere near strong enough for a hardtop. The uprights on mine are 2 1/4" diameter

have to wonder why they went so big,
maybe they had a lot of it on hand,
requires less bracing welding=labor.

my t-top is just 1 1/4 emt and plenty strong,
its all a matter of where you weld the bracing.

 

[tashasdaddy]

Re: Quickie hard top project

look how some T tops are designed. that is basically what you are building. the windshield is going to deflect a lot of air force under the top.

 

[erikgreen]

Re: Quickie hard top project

Yeah, I'll be putting a lot of effort into making sure it's held down well. I am going to angle the front of the top down, both so it's not resisting the wind during a hole shot and so airflow helps push it down against updrafts.

Removing the windshield and replacing it with plastic is looking better and better...

More pics later today.

Erik

 

[erikgreen]

Re: Quickie hard top project

Okay, time to get some pics up.

As mentioned, I wanted a hard top for my boat:

...and I didn't want to spend a ton of time on it, but I did want it to look good, either factory or a quality custom job. I honestly don't think it'll look that perfect, since I'm still improving my techniques for construction in a lot of ways, and I tend to experiment a bit, but hopefully it'll be functional.

Design goals:

• Keep out the sun and rain
• provide a place to mount antennas, lights and a hailer on top
• provide a place to mount an electronics box on the bottom
• Look good

I started with a rough measurement of the size of the area to cover. On this boat, I wanted a top 7 feet wide and 5 feet deep. That'll cover from the windshield area about a third of the way back to the stern area.

I adjusted dimensions to allow for a pointy front (to match the windshield line) and then cut the outline from spare pieces of 1/4" Plytanium XL floor underlayment... this is a 5 ply baltic birch plywood, which is waterproof and nearly void free (both qualities you want for a floor underlayment, if you think about it):

It's sitting on a couple of 2x8 sections to give me some ideas on curving the top. I decided a bit of curve would let it drain better, look good, and also add strength. So I curved the sides down by about an inch and a half.

The weight of the plywood was enough to curve it in the middle, like so:

It's sitting on a couple pieces of pink foam sheet that I had handy (actually I had no where else to put them, so they became a table).

My first attempt at this thing was to just try forming the curve I wanted then heavily glassing the underside of the top. It would then hold its shape so I could flip it over and glass the top. A few supports and I'd be ready to fair and paint it. I tried using this stuff:

Which is some 3208 90/90 biax cloth I got in bulk scraps on ebay... it's a great deal for glass, if you can use the heavy stuff for anything. I found out why it's not used more when I tried to glass it.

This is what the average piece from the box looks like, mat side up:

It's pretty big, and covers a good space.

Laying out glass over the whole thing, I used maybe a third of the box, which is less than I was expecting.

I used the wooden bracket thing on top to make sure the top was fully curved all the way across.. I didn't want the wider scrap of wood curving less because it was effectively stiffer.


to be continued....

 

[erikgreen]

Re: Quickie hard top project

So, there I was cutting glass.....

By the way, if you haven't discovered these things yet and you're cutting glass with a scissors, you need to put down the keyboard NOW and go buy one. You can thank me later.

They cut in one pass, straight, no fraying, can cut multiple layers of cloth... perfect for glass work.

Anyway, I got out some spare poly resin (Bondo brand, actually) and gave wetting out all this glass a shot.

I got about halfway through the glass and all the way through about a gallon of resin when I realized this wasn't working. Bondo is too thick to easily wet out this cloth, and also this stuff drinks resin like it's been dying in the desert for a month.

So, maybe if I had a better (thinner) poly resin or a lot more of it, this would work, but I decided to chalk it up as an experimental mistake.

I peeled the glass off after the resin cured and tossed it... good thing I didn't spend much on it or the Bondo.

So, now I still had my wood and now I knew I didn't want to just plaster glass on and go. I decided to apply the knowledge of cored construction I got from my scratch-built boat plans and essentially build a shallow upside-down hull.

First step was to cut some "ribs" out of 1/2" Arauco plywood.. this is a plantation grown plywood with few voids and a nice sanded surface. I decided to keep the 1 1/2" curve.

The easiest way to lay these out was to draw one on the plywood using a batten. I measured out the length I wanted and used thumbtacks to mark the end points. Then I took my batten (which is a length of plastic screen edging that looks like wood but is very flexible) and stretched it between the two end points and a center point 1 1/2 inches up, then traced that line (pic is sideways):

Which gave me the outline of the part I wanted:

I cut out three of them and laid them in place on the wood of my top:

So far so good. I also would need edging to reinforce the stiffness of the top and make it look good. I cut strips of the same plywood of the right length and glued them in place on the top:

....to be continued...

 

[erikgreen]

Re: Quickie hard top project

... and then I glassed them in place with some 17 oz biaxial tape I had. Note that this isn't 1708, it's just the biaxial part.

I also taped the seam between the two pieces of plywood, being careful to ensure the curve I wanted was present while curing:

I used a mix of epoxy and wood flour for glue... it's about my favorite stuff, since it is structural, dark enough to spotlight bubbles in the joints, and is cheap and relatively non toxic. I worked wet on wet, forming the fillets and then glassing over them, ensuring I didn't have to sand them to avoid bubbles. Here's a pic, although this fillet is way too big (waste of epoxy):

The fun thing about mixing peanut butter from epoxy and wood flour is that it actually *looks* like peanut butter:

Quick side note: I had been using my 3/8" drill with a paint mixer for stirring, ensuring I got a full mix of the epoxy, then mixing in the wood flour. This was ok but got my drill covered in epoxy, plus it's really hard to control and messy.

So I went to the local surplus store/thrift shop and picked up an old hand held kitchen blender. It's got two beaters, is small and light, and cost about $5. Works great, is controllable, and is geared down so it mixes even thick fillers well.

Back to the top..

Once the sides were glassed in I did the same to the ribs so the glass would overlap, being careful to pull the top into contact with the ribs so I'd get the curve I wanted. Another day of curing passed.

Next I wanted to put edging on the front. But instead of just vertical ply like the sides I wanted an angled front edge, mostly for looks. I chose about a 30 degree angle forward of vertical, cut some more ply strips and angled them in the table saw.

Then I had to figure out a way to clamp them... I didn't think this through so well. I ended up making about six angled wood blocks that I could clamp to the top and screw into through the edging, which held it in place until the epoxy glue "spot welding" cured:

So I got the front strips on, and glued on a thin strip on the back edge (flat, not standing up) for stiffness. The piece on the back was going to be straight, but I liked the look of a scrap I had from cutting the ribs, so I used it.

...to be continued...

 

[erikgreen]

Re: Quickie hard top project

...Then I stuck the whole mess under a heat lamp to cure and left it a couple of days:

I decided just for good measure I'd cover the uncovered wood on the bottom with a layer of 8 oz glass (that I had a lot of). I didn't have a foam roller handy, and in a fit of optimism I figured I'd do just as well with a disposable paint brush. Ick.

So, after it cured, I sanded down all the bubbles, high spots, and extra resin using a belt sander:

Lots 'o white dust, so I did it outside wearing a respirator.

At least the top curve is looking good:

Okay then, at least the bottom is done. Sorta. I decided to brush on some extra resin to smooth out the bubbles and such. Still no roller. Will I ever learn?

I don't have a pic of it here, but what I did was try out some white pigment I had for epoxy or poly. Basically it's supposed to color the resin and prevent chips from showing a different color. I figured what the heck since I was going to cover up the bottom with a head liner cloth anyway.

It came out "ok"... like every other pigment I've used in epoxy it tended to separate unless mixed very well, and had to be applied thickly to ensure you got a solid color... I was only doing one coat anyway, so I put it on thick. It's smoother than it was and various shades of white on the bottom now. At least it's fully sealed.

I ended up going into my second gallon of epoxy resin before I was done. Time to go buy some (*#$(*# rollers so I can do this right.


Okay, got the top back inside, other way up on the "table":

This side looks much better, and I'm going to be picky about it so it stays that way. No accidents or experiments allowed, the plan at this point is to fair over the gross surface problems including the joint between panels, fill a couple small cracks in the knots (the narrow piece at the back of the top is the B side veneer, poor planning on my part) and then apply two layers of 8 oz glass as smoothly as possible.

The top gets a bit less glass and strength than the bottom since it mostly has to resist abrasion and the occasional bikini clad young lady climbing up to have a look around.

Step one was a light sanding of the whole thing, followed by application of fairing putty to the joint and other spots that were obviously low... fairing putty in this case is epoxy and 3m glass microbubbles. Very smooth and easy to sand, but you need to wear a mask for particulates (they're silica).

So once I got the putty smooth and level it was time for glassing. I pre-cut five pieces using the roller knife and started in.

My favorite technique for glass (that gets the optimum resin in place, wets the glass, and avoids bubbles) is:

• Wet the wood with a thin layer of epoxy using the foam roller, which seals it and ensures it won't draw resin out of the glass
• Lay the dry glass in place on the wood. The thin resin layer permits repositioning as needed a couple times, but also is sticky enough that the glass stays in place while being adjusted
• Use the roller again, without any more resin, to push the glass into the resin and wood, and roll out bubbles. Adjust the glass to remove folds as needed
• Wet out any remaining dry areas with a bit of resin and the roller.

Using this method I put five pieces of 8 oz glass on the top using a total of about 1 quart of resin... much less expensive (and lighter) than the bottom side:

So that's where I'm currently at. Next steps are:

• Trim the glass at the edges
• apply a couple of "patches" where the glass I put on wasn't long enough (one piece got cut short)
• Check and shape the front corners for smooth transitions
• apply glass to the back and side edges in narrow strips to seal the edges of the plywood

Then it'll be structurally done, and time for cosmetic work. The bottom I'll leave alone, the top side will get:

• Fairing putty as needed
• Long board sanding
• putty touch-up if needed
• Primer
• Sanding
• More primer as needed
• Sanding
• first coat of paint
• more sanding
• final coat of paint

It's going to be painted white.

While I'm waiting for the layers of stuff to cure I'll be working on welding the legs for this thing.. stay tuned for more info on that. I'm nervous about getting that much aluminum welded and looking good... I guess the backup plan is steel tubing, which I'll have to paint... hmm.

Erik

 

[Tiwaz]

Re: Quickie hard top project

Looking good

 

[erikgreen]

Re: Quickie hard top project

Thanks.

Tonight I put some glass on the edges of the wood to seal and protect it. I also tried out some experiments on clamping glass to make it round tight turns... we'll see how they come out.

Tomorrow I should start fairing.

I also did some more practice welds, and I've decided I'm just not good enough at welding aluminum yet to try and make the legs out of Al tubing. So I'm going to go ahead with steel.

I haven't decided on diameter yet, the simplest would probably be 1 inch since I have bending dies for it, probably in 11 gauge (.120) wall thickness. I can afford to get enough of that to make the legs in ladder style, and I have some stainless pipe that I can make the top part of the frame from.

I'll have to finish it carefully... probably spray galvanize it then paint. But I'm sure I can do the welding fairly pretty, and the steel will be nice and strong

Erik

 

[Tiwaz]

Re: Quickie hard top project

Erik, anymore pictures?

 

[erikgreen]

Re: Quickie hard top project

Not quite yet... I spent some time on it last night, since it's one of the three nights this week I'll get to work on things.

I did get the top primed so I could see where finish sanding is needed, and I've started welding the support frame together out of steel tubing.

I'll try and take a few pics tonight, along with a pic of my skeg and some pics of the old parts another person wanted to get from me.

I also have to prep for going out of town again next weekend for more boating and diving... busy part of the year, I tell ya.

Oh, and I found out I need to replace the lower shift cable on my stern drive and fix an electrical problem in the boat too. I need to invent a couple new days of the week to get all this done

Erik

PS: Quick update on the "experimental" clamping... it mostly didn't work well. The best success was with some sand bags, but for the most part I got bubbles. Next time I'll have to vacuum bag it.

 

[jonesg]

Re: Quickie hard top project

another way to go around tight corners is to tack the cloth down with cyano super glue. then pull it tight over the corner and tack again, apply resin and sand the tacked areas off later.

Another way, let the cloth drape over the edge of the corner, sand off the flash when cured and do the same from the other direction.

at the actual corner joint there will just be resin but it will be sealed.