Bertram 25 Floor and Chine

[Andre205th]

Hi everyone, I’m starting to build my B25 back up from the stringers. I have hull with two stringers right now. On the original molded floor there is an offset that drops the floor below the chine onto the stringers without touching the chine. I canny think of a way to replicate this offset floor when I’m building the floor back into the boat. Does anyone have any experience with installing a new floor like this? I can build the floor and have it contact the hill below the chine then glad over the chine but I’m not sure if this would cause a structural issue. Based on the stringer height I may have to cross the chine, that is , start above the chine at the stern then cross over it at bow area? Any thoughts?

Here’s a picture before I removed the offset of the floor along the hull.


Thanks,
Andre

[Andre205th]

https://www.dropbox.com/s/8if0b3h8vwcaq ... .jpeg?dl=0

https://www.dropbox.com/s/8if0b3h8vwcaq ... .jpeg?dl=0

[Andre205th]

Here is a picture showing the level of the stringers compared to the chine.
https://www.dropbox.com/s/l6x539oc3i4po ... .jpeg?dl=0

And another showing the chine rising as it ends toward the bow.
https://www.dropbox.com/s/ex79yy1x42ssx ... .jpeg?dl=0

[CamB25]

I think you are referring to the z-section that runs all around the deck to hull side joint. If so, try to keep that piece on the boat when the deck is cut out. If it is gone, it can be filled with section of Coosa, or similar. Glass hull side over the filler and onto the deck. It is a REAL PAIN to FAIR this joint. Took me forever to get it reasonable. Here is a picture of my boat before significant fairing:

https://www.amazon.com/photos/shared/o0 ... phceecahKd

[ktm_2000]

I left the joint which Cam describes intact. My plan is to raise the height of the main stringers to match the height of the lip, then place my new deck panels on top.
https://photos.app.goo.gl/LVejG145KhToTnf97

[CamB25]

Yes! Save that lip and save a few years of fairing time! WooHoo!

[Andre205th]

Thanks for info guys.

I’m think about putting in the floor sections an wondering how to glass the hatch gutters. I plan to use 1708 or woven on the floor panels and hatches where they are flat but I’m not sure how to glass the small radius of the hatch gutter. I know I can do it with CSM but from what read that’s not strong or durable enough. Can 1708 make 6 small 90s within n a couple of inches? Planning to use 1” foam for everything. Does this have to be done with a vacuum setup?

[ktm_2000]

Andre,

In my boat I am planning on re-using a portion of the fuel tank hatch, the concept is to cut around the hatch leaving an excess of 4" around the perimeter then taking the core out of that 4" of excess. From there I will fit the hatch into the new deck and grind down the core where the excess of the hatch perimeter is and make it so the hatch sits flush. I would then glass over the joint so both pieces are tied together.

here is the hatch frame after I cut it out of the original deck and started to remove the core from the back side. The top side glass is about 1/4" so I won't have to remove much. I have not yet modified it to cut down the size, my fuel tank hatch was the 2 piece one and I only plan on using 1/2 of it so I will need to modify the frame to match.
https://photos.app.goo.gl/bpVR3aCFZJr9LcZN6

my buddy did this on his seacraft, these are pics prior to glassing in the nidacore deck. As is the deck is strong without the top tie in glass.
hatch frame
https://photos.app.goo.gl/wzZnDVhVzomH1YgK9
Installed in the boat
https://photos.app.goo.gl/mHiW9BTqhnnRwXAV6

[Andre205th]

I have 4" wide 2# foam bulkheads(hollow, made from 1" foam). I made them to slip over the two existing stringers. I plan to put 5 layers of 1708 on each.
How does this sound, too much? not enough? After glassing them individually I'll tab them into the hull with fillets.

Also, my floor will have a curve to it. If I put a straight edge from the floor support at the stern to the bow floor support, there is about 5 or 6 inches gap in the middle of the boat between the straight edge and the bulkhead. The bulkheads follow the top of the chine. How can I put down a floor that will bend or curve as needed. I was planning to use 3/4 marine ply and glassing both sides but if I glass the ply on both sides I pretty sure its not going bend. Has anyone dealt with this?

[scot]

It appears that you reinforced the protruded chine from the inside? If so, good thinking. The chine on the 25's is not adequate. They commonly crack longitudinally (as mine did). I had to remove the gelcoat and add (4) layers of 1708 to the exterior to rebuild the chines on mine. The hull side, some of the deck load and any super structure sitting on the cap is supported vertically by this chine, which acts like an accordion... and eventually cracks. IMHO the decks need support from the hull, not the sides. I added transverse gussets to support the deck and stiffen the hull. These are simple additions. 3/4" ply in a few strategic locations tabbed to the hull and into the sides. Very little time or money for piece of mind and a much stronger boat.

But, I'm fanatical about hull strength. Don't think much about weight, as I don't care for a light boat. Heavy boats burn more fuel, go slower and are much more pleasant to spend the day on My boat came from the northern Gulf, and I will be using it in the northern Gulf (2020 launch target). The wave period is SO close in this region it literally beats boats to death. 40 years of pounding took it's toll on my hull.