TOPIC: 1971 Penn Yan Hurricane runabout restoration

My dad bought this boat new and passed it on to me. It still has the original 50hp Mercury 500 outboard on it. Since this boat has a lot of fond memories for our family, we decided to restore it so the grandkids can enjoy it too. Here is a picture of it from the 1969 Penn Yan brochure:

Unfortunately age and some rot caught up with it in spite of my dad's excellent care. It developed a soft spot in the floor that I eventually put my foot through a few years ago. Here it is when i started:



And here is that troublesome spot that started it all:

A close-up shows there isn't any foam under the plywood floor like we thought there was, and the wood is wet and rotting...

Some probing and peeling and this is getting pretty ugly pretty quickly!

Back to the floor repair, I removed the 3/8" plywood floor to reveal... fiberglass ribbon candy? Penn Yan simply laid in the woven roving like a wet blanket between the hull and the floor stringers. Think corrugated cardboard, this made a fairly stiff floor and hull combination. In the picture below I have already removed the wrap over the keel. I found it was wet even after four years in storage.

Inspecting the fiberglass corrugations showed splits and breaks where they met the hull under the seats. This method worked OK in other areas of the floor but not under the seats where waves put a lot of stress on the hull and corrugations. This explains the crunchy sound from the floor when going over waves and wakes!

Below I have removed the floor stringers and fiberglass ribbon candy:


A look at what remains of the aft end of the floor. That is the fiberglass skin left after I cleaned up the wood mush. Penn Yan made a mistake in using 3/4" plywood for the triangular end pieces. Over the years the plywood was wetted by bilge water seeping through the fiberglass covering. It turned to mush and allowed water infiltration and rot to continue into the rest of the floor.

After a couple of days of grinding and sanding and cleaning up the huge dusty mess I made, here is the inside of the hull ready for reinstalling the floor. I got really lucky with this project: the transom is intact, no cracks and rot free.

Another view. The remaining floor showed no signs of rot and we decided a butt splice in the keel would be plenty strong. The crosspiece at the edge of the floor cut will be replaced too.

My dad and I fabricated replacement wood parts, identical to what Penn Yan had installed except for the aft end triangles. Figuring why mess with 41 years of design success (except for the rot), let's make it like original except for a couple of improvements? I used solid wood for the triangular end pieces and notched them to catch the ends of the floor stringers. The original stringers were nailed into place at the face of the plywood triangles. OK for boat production where time and effort cost money, but not the best way to do it structurally. Here is the new wood, which is african mahogany, being final fitted to the hull.

I cleaned the hull interior with acetone and began installing the replacement structure. Here I epoxied the keel and triangles in place:

After applying a 3/8 radius fillet at the hull and rounding over the top edge of the keel with 1/8" radius round-over bit, I applied biaxial fiberglass cloth with epoxy resin. The fillets and rounded edges allow the fiberglass to lay flat and maintain full contact to the surfaces without wrinkles or air pockets. The epoxy resin is easy to work with, nearly odorless and much stronger than polyester resin in this situation. This method will be stronger than the original glass with slightly less weight.

Wow, what a mess! Looks like you have it under control now though, MPY. Welcome aboard, btw.

Thanks! Glad to be part of this community, hopefully this project can help others, too. Yes, quite a mess but things are really coming together now.

Continuing with the floor reinstallation, the rest of the wood is installed.

Here is the other slight design change made to stiffen up the hull like original. Pieces of closed-cell core foam were fitted between the floor stringers and the hull. These provide a surface for applying new fiberglass "ribbons" between the floor stringers and the hull. Bonding the fiberglass to the foam will keep it from flexing and breaking like the original stuff did. Essentially, each floor stringer becomes a hull stiffener. This is overkill by modern boat design standards. But it is a convenient way to solve the problem of the broken fiberglass ribbons that I found.

These got 1/2" fillets at the hull, the floor stringers were rounded over at the top edge, and then wrapped with the same biaxial cloth used on the keel. This stiffened up the hull tremendously. The hull was very flexible when it was stripped and I had to be careful not to permanently deform it when reinstalling the stiffeners.

After all of the supporting structure was completed, it was time to install the new plywood to the floor. The original plywood was 3/8" 3-ply and what appeared to be exterior grade fir. It did OK except for where it was rotted. But newer, better materials and processes are available, so why not use them? The new plywood is 3/8" 7-ply meranti Hydrotek marine plywood. Very strong, rot resistant and nice to work with. It took nearly an entire 4 x 8 sheet. First I sealed the underside with epoxy resin. Then I measured offsets from the keel/centerline to each side at every foot along the keel. I used two battens laid across the boat on the floor stringers, pushing the ends out until they just contacted the hull. I then clamped the battens together and marked the centerline on the battens. I drew the centerline and 1 foot stations on the new plywood and then marked the offsets on the plywood. I connected these marks with a wood batten, drew the lines and cut the plywood. I left 1/2" extra stock at the forward end of the new plywood and scribed it to the existing floor. After trimming this, it fit in place without any gaps and no further trimming needed. I got lucky with the aft edge as it lined up flush with the triangular end pieces. A 3/8 radius roundover at the aft edge made it ready for the fiberglass overlay.
The new plywood was then epoxied and screwed down every 8" along the keel and stringers. This new floor proved to be very solid.

I get the feeling "this ain't your first rodeo" MPY, very nice work there. Thank you for sharing, looking forward to seeing more.

Penn Yan had finished off the floor by fairing the edges with a bondo-like filler material, then a layer of what looks like 6 ounce cloth fiberglass with a coat of blue gelcoat that has a white gelcoat spatter finish. I want to duplicate this overlay including the gelcoat finish.

Here the floor is being finished off by applying Bondo filler along the sides and front seam of the floor. It had to be worked into the valley between the edge of the plywood and the hull, then built up in layers until it faired in like the original floor.

Here the filler is done including final block sanding:

Next up is the fiberglassing of the floor and the exposed portion of the keel. All of this will be done with polyester resin and gelcoat to match the existing boat.

Actually MarkS, this is my first ever boat repair. I have worked on ships as a shipfitter, including lofting, but that was working with steel. Some of those skills carry through, but not the fiberglassing. I've been a big fan of boat restoration projects and boat building so that helped with studying what worked and what didn't.

Now comes the fun part, installing the fiberglass overlay on the floor. When I was disassembling the original floor, I took the time to figure out how Penn Yan put it together. Turns out the edges of the floor had an 8" wide strip of chopped strand mat (CSM) along the port and starboard edges and across the aft end into the bilge pocket. Then they laid down 6 ounce cloth over the entire plywood floor and into the bilge pocket. The exposed portion of the keel was originally wrapped separately in a layer of 18 ounce woven roving. I will install the same fiberglass overlay as original because I intend to use a polyester gelcoat finish like the original. I could have used epoxy resin for the overlay, but polyester gelcoat is not compatible with epoxy resins. One minor change from the original, I'll use two layers of the biaxial cloth on the keel board to get the same laminate thickness as the original roving wrap.

Here is the chopped strand mat applied to the edges of floor:

When applying the resin to the chopped strand mat, I chose to lay the mat down on the dry surface and then apply the resin by dabbing with a chip brush. I then used a grooved roller to work out air bubbles and move excess resin around. This worked great because the sizing holding the mat fibers together dissolves in resin and releases the fibers. Had I set the mat into wet resin and then tried to brush more resin onto it, the fibers would have worked loose turning any brushing action into a big mess. I applied the mat across the end of the floor in one piece, draped over the edge, down the triangle face and onto the hull in the bilge pocket. Here I did wet the vertical surface with resin first, which held the mat in place while I wetted the rest of the mat. The grooved roller made short work of laying the mat flat and smooth.

Here is the bilge pocket with the chopped strand mat installed. I managed to get a better lay of the mat than Penn Yan did, due to the rounded outside corners and fillets. Before putting down the mat I used polyester resin thickened with colloidal silica for filleting the inside corners.

Here is the floor with the 6 ounce cloth applied. This was a bit tricky trying to get it in place without wrinkles because it stuck to the tacky laminating resin used for the mat. This was a single piece of cloth covering the entire floor to the chines and bilge pocket.

Here is the keel board with the fiberglass installed

Anymore updates on this project available? I really enjoyed the read great work.

Actually have not gotten much more done yet because I shifted focus to the Merc 500 outboard, original with the boat. My dad and I decided to change the water pump impeller one weekend last year, and replace the fuel lines on the engine. But we found the drive shaft was rotted and had to replace it. That required tearing down the lower unit, replacing the drive shaft, replacing the shift shaft and all seals. Locating a replacement long drive shaft was a challenge but I found a NOS shaft through Marine engine.com. The power head now has new fuel lines, rebuilt fuel pump, cleaned carbs, and a new wiring harness. The outboard is now ready to run so we'll be shifting our focus back to the hull.

The floor repair is now completed. The fiberglassing of the floor was finished off with some fairing the surface flat with slightly thickened poly resin and sanded smooth. Since the interior was intended to be sprayed with gelcoat like the original, we opted to pay a pro to do it. The entire repair job hinges on a decent finish and I have never sprayed gel coat. Adrian and his crew at Knox Auto Body in Shapleigh, ME did fantastic work, matching the original color and applying the white spatter finish like original. By the way, the blue deck is all original gel coat, except for a small repair at the tip of the bow. A couple of repairs were made to the white hull gel coat, otherwise it's also original.
Here is the interior now:



Here it is with the seats reinstalled and nearly ready to go:

Update on this restoration, the last details were taken care of, the motor test run on shore and then sea trials were this weekend. The outboard runs flawlessly, the boat handles great just like I remember. We took an extended tour around the lake and had no issues at all. A family heirloom ready for many more years of enjoyment. Here it is in the water...

MousamPennYan,

WELCOME ABOARD.

NICE boat & NICE work on it, too.

yours, satx

Looks great MPY, glad to hear it went well. Thanks for sharing the "after" pic with us!

Looks Great. Not many 14 ft boats will slice the water like a Penn Yan Hurricane. You have a nice boat there.

Outstanding! Always a great feeling when all your hard work comes to fluition with a successful launch!!! Now enjoy the heck out of her!

Bob

Thanks! It was a lot of fun, first ever boat restoration, with some outboard repair thrown in for good measure...
now to find a decent pair of Penn Yan emblems, one was missing, the other is still installed but broken. It's about 15" long and made of pot metal that is chrome plated and trimmed with black paint... Anyone know where I can find the late-sixties or early seventies script emblem?

Somebody on the west coast was "re-popping" metal emblems, maybe Larry at Vintage Boat Works?

Thanks Mark, I have heard of Larry and will check with him!