1977 Formula Signa 18 TriHull, floor and transom repair.

TomToms

Seaman Apprentice
Joined
Jun 11, 2015
Messages
36
So I bought this boat in the spring of 2015. I had never owned a boat before but I saw it pop up on Kijiji (Canadian Craigslist)with all the accessories and electronics on it included for $500 I figured why the heck not. Like many people before me, I checked the engine, I checked the trailer and I inspected the bottom of the hull to look for damage. What I did not check was the transom, and I did not inquire as to why the floor was soft in some spots. I happily brought my boat home and began work on the engine (which wasn’t running). Turned outold gas and neglect were the culprits, quick tuning and some new fuel and I would say the engine purred like a kitten but it’s a 115 HP OB Merc 2 stroke inline 6 tower of power… it is more like a screeching banshee than a purring kitten. I took her out for her first voyage with me in the captain’s chair. Everything went perfectly until my father who had come with mentioned the transom seemed to really bend whenever we hit a wave. I ignored him like all good son’s do, because I thought I knew better. I took her out several times after that and luckily ran into no issues other than the tilt trim motor stopped working on me on the last run. Winter was coming so I figured heck I’ll put her in storage and figure out the problem come spring.

Which leads me to last week. Springs approaching and I wanted everything to be in good working order when the first good boating day arrives. So I disassembled the tilt trim motor and cleaned the brushes. After reassembly everything’s back in working order. As I went back to reinstall the motor I was leaning underneath the spashwell and I found a crack on the inside of the transom going between two of the mounting bolts on the motor. So I started to do some research, which got me worried so I posted a question to the general boating forum here on iboats. With some instruction from the wonderful people here I found that my transom was completely rotted, and it was only a matter of time before I would be dodging the motor on its way off the boat passed me and into the water. As you can see in the other post I linked I tried coming up with alternative solutions (aluminum bracing etc.) All of these were shot down by those smarter than myself. I also took a screwdriver to some of the soft spots in the floor and found that the floor too was rotting away. So I did a quick check of other boats available on the market, maybe I could just use a new hull and keep everything else. That turned out to be a no go as I checked a few out and in my area there’s nothing under $1000 that is in decent shape.

That brings me up to this past weekend. I decided to take the plunge and begin repairs. I’ve needed a project to work on and I have the time, and also this boat fits my needs quite perfectly. I am not doing a full restore, I don’t have the money for that. But I will be tearing out the floor and rebuilding what is necessary to get myself a solid boat for the next several years.

In conclusion I am posting this here to document my progress and also to have a place I can ask you for advice. I am brand new to all of this and will probably need some help. You’ll find some pics of my boat the day after I bought it, (I apologize for the quality my phone is not the greatest) as well as the Formula brochure page for it. If you have any advice for me before I dig in to deep please let me know.

To be continued...
 

Attachments

  • photo238788.jpg
    photo238788.jpg
    50.9 KB · Views: 1
  • photo238790.jpg
    photo238790.jpg
    48.6 KB · Views: 1
  • photo238791.jpg
    photo238791.jpg
    49.3 KB · Views: 0
  • photo238795.jpg
    photo238795.jpg
    25.8 KB · Views: 1
Last edited:

tpenfield

Moderator
Staff member
Joined
Jul 18, 2011
Messages
17,620
I would plan on doing the transom, stringers and floor. Not sure how that matches up to your idea of a partial restore or not, but it is probably what is needed.

I do not think we have seen a restore of a (pre-Formula) Signa hull before, si it will be interesting to see this one being restored. Post lots of pictures as you go.

:thumb:
 

TomToms

Seaman Apprentice
Joined
Jun 11, 2015
Messages
36
tpenfield I will do my best to take all the pics I can.

I have a couple questions to start. The floor was completely fiberglass. I have heard of some people just replacing with carpeted sections of ply with a sealant on them. Is this a viable option? It would save a lot of money in glassing. Or is the glass something that is necessary for structure? I of course realize that the transom and stringers need to be glassed in. I'm just wondering about the top floor layer.

Also, I took some sections of the floor out already, the foam was completely soaked and any wood that was exposed is rotten through, But the two main stringers running the length of the boat seem to be complelty solid. I drilled some holes and am getting fresh dry wood. Is this common?
 

tpenfield

Moderator
Staff member
Joined
Jul 18, 2011
Messages
17,620
Not sure about the floor construction of the Signa, but for that vintage and even later vintages of Formula boats, they had fiberglass over wood floors until about 1987 when they went with the 'clam shell design', which had the floor as part of the deck assembly (not the hull).

Pictures would help us see what you are seeing.

Very unusual that stringers surrounded by wet foam, etc, would stay dry, but there could be the exceptions. Just don't short change yourself on the restoration work. Fixing it thoroughly once is still cheaper than fixing it partially twice.
 

TomToms

Seaman Apprentice
Joined
Jun 11, 2015
Messages
36
I will take some pics later on today when I can get back into the garage to do so. What It currently has is a completely sealed fiberglass layer with plywood underneath. Does this mean the fiberglass over the wood is used as a structural thing?
 

jbcurt00

Moderator
Staff member
Joined
Oct 25, 2011
Messages
24,829
What It currently has is a completely sealed fiberglass layer with plywood underneath. Does this mean the fiberglass over the wood is used as a structural thing?
Where?

The deck (floor)?
 

TomToms

Seaman Apprentice
Joined
Jun 11, 2015
Messages
36
My apologies, yes the deck is a layer of fiberglass that is tied into the hull, under the fiberglass there is plywood.
 

tpenfield

Moderator
Staff member
Joined
Jul 18, 2011
Messages
17,620
It might be more accurately described as a plywood floor with a layer of fiberglass over it. There has to be a restoration thread or two of a Signa of similar vintage on the Internet somewhere. It would help to see what the guts of this boat look like before you open it up. Maybe a Google search will find something.
 

alldodge

Moderator
Staff member
Joined
Mar 8, 2009
Messages
40,581
I had a 76 Signa years ago with an inline 6 in it. Had to replace the transom, floor was still in good shape
 

TomToms

Seaman Apprentice
Joined
Jun 11, 2015
Messages
36
No Title

I will do some searching.

AllDodge, did your transom have solid wood covering the entire transom, or did it just have a section of wood directly under the splashwell. I've added a pic, the red lines outline the wood, the rest is just fiberglass.
 

Attachments

  • photo238789.jpg
    photo238789.jpg
    63.2 KB · Views: 3

alldodge

Moderator
Staff member
Joined
Mar 8, 2009
Messages
40,581
I will do some searching.

AllDodge, did your transom have solid wood covering the entire transom, or did it just have a section of wood directly under the splashwell. I've added a pic, the red lines outline the wood, the rest is just fiberglass.

Mine covered the entire transom and it also it bowed outward. At the time I had it replaced by a company and they made it flat, which also caused then to fill in the gap between the top and bottom with silicone. I was not happy
 

TomToms

Seaman Apprentice
Joined
Jun 11, 2015
Messages
36
I took the time to take some pics, I had already started some work before I took them so I apologize for no real before photos other than the ones from last year. Also I again apologize for the bad lighting, my garage is dark and old and I only have one bulb. It makes the grime in the boat look worse that it really is. Here?s where we are at.

SYJUyKi.jpg

8ouMeFP.jpg

E7jmv0D.jpg


I have the cap off partially, I am using ratchet straps from the roof to move it up evenly from all sides. Getting it down later may be an issue as ratchet straps don?t let down slowly, but I cross that bridge when I get there.
HFWGMLt.jpg

v0zoDas.jpg


Here?s the inside of the boat as it sits now, don?t mind the mess of tools.
UUGDDbR.jpg

3P0mwDL.jpg

njzIJtK.jpg

I used winter shrub cover over the engine to keep the dust off it while I work, as I can?t move the engine to another location.
You can also see where I started ripping up the floor in that last image. The gas tank is still in and full of gas so I will need to find a way to remove the gas to make it lighter, perhaps I?ll siphon, I?m not sure.

Onto the transom. Here is the only section of wood in the entire thing, the top view shows it more clearly.
OtdW7R2.jpg

pJ0To1w.jpg

oEl5YBX.jpg

afv41zU.jpg


Quick image of the shoddy fiberglass job that held the transom to the cap. The wood was so rotten that it peeled away when I started jacking the cap off.
Shso7kx.jpg


I have been tapping the stringers and they seem extremely solid. At least length wise, so I drilled a hole in one and it has clean shavings coming out. I stuck a screwdriver in the hole so I can remember where I need to reseal it if the stringers end up being ok to keep.
dYx4Vju.jpg


Little bit of a puddle forming in the bottom of the boat after I started to remove the waterlogged foam.
7xjNGhr.jpg


All the screws and rivets in the cap have been removed but the front is being very stubborn, I?m thinking it may be glued onto the hull somehow.
92S2mE6.jpg


That?s all the images for now, here?s a running total of man-hours and money spent:

Hours: 16
Money: $90 CAD
 

TomToms

Seaman Apprentice
Joined
Jun 11, 2015
Messages
36
How do you guys feel about Nida-Core honeycomb sheets? There is a supplier a few hours from me that is clearing out 4'x7' 1/2" sheets at $20 each. I am thinking of doing the deck and stringers with it. Of course for the stringers I'd double up to get a full inch at least. What are your thoughts?
 

alldodge

Moderator
Staff member
Joined
Mar 8, 2009
Messages
40,581
How do you guys feel about Nida-Core honeycomb sheets? There is a supplier a few hours from me that is clearing out 4'x7' 1/2" sheets at $20 each. I am thinking of doing the deck and stringers with it. Of course for the stringers I'd double up to get a full inch at least. What are your thoughts?

Guess no one here has used it. From what I can find, which isn't a lot, it appears to hold up well for those that have used it. Found a few folks using it as decking, no transoms found. I would say it could not be used where lag bots are needed, there just isn't anything inside for the threads to hold on to. All fasteners would need to be thru bolted to something on the other side.

Now if it is on the deck and glassed in, I think it would be fine, but just my guess
 

tpenfield

Moderator
Staff member
Joined
Jul 18, 2011
Messages
17,620
How do you guys feel about Nida-Core honeycomb sheets? There is a supplier a few hours from me that is clearing out 4'x7' 1/2" sheets at $20 each. I am thinking of doing the deck and stringers with it. Of course for the stringers I'd double up to get a full inch at least. What are your thoughts?

The forum member imp0ster is currently doing a rebuild/repair using the NidaCore Honeycomb. Normally very (very) pricey, but light and will not absorb water, etc. So, if you can get a bunch for short money, I would take all that you can get or would need. There is also similar products like Coosa board and DiviniCell that are foam-based, the higher density stuff could be used on compression areas like decking, transoms, etc. The lower density stuff would be good for stringers and bulkheads.

If I were ever doing a full restore, I would use synthetic, not wood.
 

ondarvr

Supreme Mariner
Joined
Apr 6, 2005
Messages
11,527
Honeycomb works well for a floor, but not for stringers, well it works to use as a shape, but offers no strength in that direction, it doesn't work well in compresion either, so it's not used in transoms without some modifications.
 

sphelps

Supreme Mariner
Joined
Nov 16, 2011
Messages
11,429
At 20 bucks a sheet for a composite no wood deck I would jump on that deal .... You may have to do a little extra for your seat mount area's though ...
 
Top