New Hard Top

[Ambler27FC]

I am planning on building a new hard-top for the back section of my A27 this year. I already have a hard top that has an aluminum frame and semi translucent cover. Very practical, but a little worn and not aesthetic for the boat. The new hard top would butt up to the forward cabin and match the lines of the boat. I would screw into the hard-wood at the back of the production hard-top then fill and glass over the seam.

I've read through all of the threads on this forum, plus a few others (some of which were rather toxic) and still have a few questions. Any suggestions would be much appreciated.

I have a good template for the shape at the back of the cockpit hard-top. The plan is to match this, and then blend to a slightly more rounded profile a few inches back (the production hard-top is very flat). The new hard-top would be strong enough to support the weight of a person - for maintenance or a dinghy. Thinking about 1/8" of fiberglass top and bottom with a .75-1" divinycell core and hard-wood for ribs and at stress points. The edges would be boxed off to mount channels for corded canvas.

So, looking for any advice on the following:

1) Create a mold or glass over a structure? The mold would create a better external surface, but would leave me trimming beams to irregular surfaces and adhering with something like 5200.

2) Glass schedule? What is the best way to build up to 1/8?

3) Poly or Epoxy? I really like epoxy, but resin is cheap. I will be painting the entire end product, so I think it is the strength of the bonding that decides it.

4) Is Divinycell a good choice? I was worried about bonding. Also considering Coosa and balsa (I'll be epoxying all through holes).

Apologies for the long post...

[Ambler27FC]

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Very rough layout - I think about 7' x 6'.

[tego]

Great to see a A27FC post on here again. I thought most other 27 owners had migrated elsewhere. I'm working on my hardtop again after my mate finally decided that she would kinda like one. One of my concerns was to make the add-on removeable to allow pulling the engine easier. I'm going to make a new 1" teak board on the aft end of the old top to reinforce the old top at that point and that should allow me to attach the new top using "T" nuts behind the new 1" board. I'm going to make the new top as flat as the factory top (mine has a very slight curvature to shed water). My new top will slope down going aft about 1" to help drain the rain. Otherwise, it'll look like the factory top outside with some ribbing underneath and a core of about 3/4". My factory top has a 3/4" end grain balsa core that wasn't bonded very well (it separated) so I had to inject epoxy into it at several places to re-solidify it- it's very strong now. Making a good mold is tough so I think I'll glass over a structure for the new one. I don't use poly resin for anything anymore so I'll be using epoxy. My layup schedule will be a layer of bi-axial cloth with a couple layers of heavy mat on top followed by a good fairing compound that I can "longboard". Underside will be a couple layers of heavier mat and a fairing compound. Back about 5 or 6 years ago when I started this project, I thought about a small "drip gutter" along the outside edge but I'm leaning against that idea for now. My coring will be a structural foam, as it bonds very well and is quite light weight-wise. I've worked on a lot of boats and yachts and anything I build now, I build so I can access anything under it when something breaks. I can say from experience that MOST designers don't do that, especially on the larger vessels. Keep us posted on your progress and PM me anytime if you want to talk about a project. I love these boats! Ben "87 27FC

[motthediesel]

I’m glad to see this thread, as I’ve been thinking about building a hardtop for our 27FC as well. We have a nice bimini now, with Eisenglass and screens, but it’s starting to show it’s age, and we never take it down, so we’re thinking of replacing it with a hard cover. The other reason to go with a ridged top is so we can put hand rails up there. You feel quite exposed on the narrow side decks there with nothing to hold onto.
I am planning to use a honeycomb core material like Nidacore. It’s light, easy to work with, and fairly inexpensive as well. I would use epoxy resin, as that’s pretty much all I deal with now.
If you want to see a fairly detailed description of building a hardtop from this material, I would recommend a guy named Teal on YouTube. His channel is called “Onboard Lifestyle” and he builds a very large top for his sailing cat on his videos. I’ve been working on wood and fiberglass boats my whole life, and this guy impresses me, he has serious chops as a builder.
Check it out, and keep us updated on your progress.

[WillieC]

My hat is off to you guys undertaking a new glass hardtop. Some very good points made here about being able to work on it later. I am currently rehabbing my who knows how old custom BC hardtop on on A25. It will have removable grab rails without through bolts for rebedding when it becomes necessary. It will have integral wiring for recessed ceiling lighting. Complete with a new (using recycled cedar closet liner) cedar paneled exposed interior to cover up the less than attractive congealed snot underside.

I seriously considered starting from scratch but my experience with glass is very rudimentary. I look forward to seeing how these projects turn out.

[WillieC]

In progress.

[WillieC]

I’m so glad I just have to handle it rather than building from scratch. First, assemble a simple rotisserie.

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[SalishAire]

It looks like most of the posters have MUCH more fiberglass experience than we do but having just glassed over the open "skylight" over the pilot house we will add what we have learned. The glassed in section over the pilot house uses a Coosa board core and epoxy with 3 total layers of glass (1 fine weave fabric + 1 fine roving + 1 fine weave fabric) above and below. To bend the Coosa board we saw cut partial thickness lines on the concave side and then filled them with putty prior to glassing. Since we planned to coat the top of the roof with Kiwi Grip non-skid paint we didn't worry about a perfectly smooth surface finish. A challenge was that the arch of the roof had drooped over 45 years. To correct the droop we initially pulled the sides back in with a ratchet strap then inserted an oak truss on the under side and screwed it in place which nicely corrected the droop but I kept hitting my head on it. We are now in the process of building a Stamoid fabric cockpit surround. I welded up a forward and aft arch that will support the fabric (the forward end of the fabric will connect to the fiberglass pilot house roof) and radar and folded dingy or kayaks. The forward arch was also designed as a ladder truss and lifts the pilot house roof so that the oak truss could be removed.

[Ambler27FC]

Thanks for all of the inputs. After a day’s though I think glassing a structure would be easier. Maybe ¼” plywood to define the curves with some 3/4” foam glued to the back for lower weight and rigidity with reasonably spaced beams to guarantee adhesion between top and bottom.

Epoxy it is – I was leaning this way, but glad for the feedback.

Consensus seems to be layer of biaxial for the outer surfaces and thicker material to thicken things up. Any cloth weight recommendations on the glass? Fairing compound and sanding to make it look pretty.

I am very curious to see the condition of the wood at the aft end of the production hardtop when I tear everything apart. I have some separation on the hard-top over the helm too. My interpretation is that there is an outer form with balsa and an inner form that were glued together. Pretty, but it makes me appreciate work-boats with a rougher interior.

Tego – I think your Mate has it right. I can’t imagine a boat without a hard-top. Don’t know about you, but I get plenty of sun already. Registering a reminder to plan for external electrical wire-ways, very smart. BTW – the engine can go out the side by forklift.

MottheDiesel – thanks for the video reference. The good ones can be hard to find. I though honeycomb was for professionals, but will check it out. Agree the hand holds are critical, and I would go custom for full length if I have to.

WillieC - You look like your neck deep in this already, and doing something much more substantial than I was planning. I see a hatch port – something to add.

SalishAire - I am not familiar with the layout of an A25, but a previous owner installed vertical 1” tube right under the back arch, just behind my engine hatch. It supports the shape of the top and houses wires for the solar panel, but most notably it is an exceptional hand-hold in bad weather.

[Bearkeley]

We were the lucky owners of MaryJo, after Captain Vic did all the hard work on modifying the boat and adding the hard top. We don’t have the aft cabin (removed by po) and have enjoyed the full enclosure during our extended cruising. Here’s a picture of our MaryJo and our Thanksgiving dinner in the Everglades, fully enclosed from the bugs!

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Be sure to look for Vics posts to get some history on his work if of interest.

[Ambler27FC]

Mary Jo is an incredibly smart layout for this size boat. Wish I had the skill and time for that kind of transformation.

A survey of hardwood prices has changed my approach. Will be gaining experience building a mold and researching composites a bit more.

[DesertAlbin736]

Mary Jo is a nice look vs the aft cabin. Like the Europa style trawlers vs the two cabin trawlers.

A survey of hardwood prices has changed my approach. Will be gaining experience building a mold and researching composites a bit more.

I've talked about how I did our hardtop in past threads & replies. It's been six years since I made mine as a fiberglass layup from a one-off mould. It's held up well over the years since. However it just covers the wheelhouse T top opening like SalishAire's except with opening hatches built in. But what Ambler is talking about is more complex, so a wood frame covered with plywood (1/8th birch ply?) & glassed over with cloth & polyester or vinylester might be a better, certainly easier way.

I got out my copy of Don Casey's "Sailboat Hull & Deck Repair" book recently when working my latest repair project filling in bolt holes in the hull after removing a sintered bronze grounding plate that was busted up from sitting on top of the trailer bunk & had started leaking into the hull. Several things of note: 1) Epoxy resin & chopped strand mat don't mix well. The binders that hold the mat fibers together interfere with epoxy curing. Also, if you plan on gel coating the outside, epoxy doesn't adhere well to gelcoat. So, if you plan on laminating with epoxy use woven cloth, not chopped strand. And if planning a gelcoat outer finish rather than paint then use polyester resin & not epoxy.

All that said, if you plan to built a mold & do a layup, then I found in my experience that sheets of 1/2 inch styrofoam insulation are good for making patterns to shape your mold from, both horizontal shape & vertical curves. Common lumber & masonite are good materials to build a mold with. In my case I used a coat of gelcoat in the mold (coated with PVA release first), followed by initial layer of glass cloth, then alternating layers of 1/8th inch diviny cell foam core & chopped strand mat. I used isothalic resin rather than polyester or vinylester resin, but not epoxy. Good temperature control is key, try to keep the work environment at +/- 70 degrees or so. Bear in mind, fiberglass resin, cloth, coring, and supplies are not cheap either. A survey of costs for a fiberglass layup may be eye opening too. Over the years since 2014 I've spent more on upgrade & repair projects than I care to contemplate. Certainly much more than I'll ever hope to recoup when the day comes to sell La Dolce Vita.

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[Ambler27FC]

Thanks DA. I had remembered that mat is tough with epoxy, and that gel coat is strictly for polyester resin. Think I will stick with weaves and epoxy. I have used mat with epoxy, but it is tougher because the binder doesn’t dissolve properly. No idea on how this effects strength, but not worth the risk.

Fully aware of the other costs! The hardwood doesn’t seem like added value though. I’ve lined up 2nd rate pine for the mold. Starting the mold build this week so I can go full speed when the temps are high enough. Hope to mount the thing by late summer…

[trakus]

Just saw this post and thought I'd reply. I too am embarking down the hardtop route with my A27FC. Due to skyrocketing costs here on the West Coast of BC, Canada, and a marine labour shortage, I'm actually going aluminum instead of fiberglass. We should keep each other updated on the progress and any tips or handy additions we run into!

[Ambler27FC]

Trakus,

An aluminum frame with fiberglass top? I’ve seen catamarans with large frames hidden under a thin fiberglass roof and also crew boats with canvas covers over a metal frame. Both seem smart. If your not worried about matching the lines of the original hardtop it gets a lot easier. I am probably going to have some stainless supports made to hold up the back end, canted to match the angle of the cockpit.

My current hard top I will likely be offering up in a year or so. Aluminum frame with a plastic overhead that needs to be refreshed. It is supported by a standard Bimini frame. Smart and practical, but I like to build stuff for no good reason.