Rebuild assumptions open for feedback - long read

[Locke N Load]

I have been in the decision-making process for way too long so it is time to make decisions, buy materials and get to work. Here are my decisions for my Seafari 20 rebuild. I am open to constructive feedback if any of my plans can be improved or are just a bad idea.

1. Coosa transom, 3 layers of 3/4" Bluewater 26 with 1708 and epoxy working from outer skin in.
1.a. Layup schedule - 1 layer of 1708 on existing skin-Coosa-1708-Coosa-1708-Coosa-4 layers of 1708 tabbing starting 12" overlap onto hullsides and sole then 9", 6" and finally 3".
1.b. Notch in transom 28" wide at top narrowing to 26" 10" down from top of the transom. This will give 27" from keel.

2. Raising stringers from console bulkheads to transom 2" by laying vinyl gutter drain on top of existing stringers and tabbing in with 2 layers of 1708. 3 layers maybe? The drains will be the chases for wiring/cables,etc. from the console and batteries to the bilge area and motor.

3. 62 gallon 72" long gas tank starting at bilge bulkhead 24" from transom to 15" before console bulkheads. Epoxied in Coosa strips to support bottom and secure sides and ends. There are no welded on tabs on the top of the tank to bolt it to the stringers. Tank is bare aluminum so plenty of ventilation openings will be made.

4. A group 31 and a group 27 battery will be located under deck in the area between the end of the gas tank and forward to the console bulkheads. This is the 15" long area with 25" between stringers that would normally be the step down area between the helm chair and co-captain chair before going into the cuddy. Plenty of room for two batteries. I will try to make this area as waterproof as possible with proper ventilation and access from a hatch above in the deck. Not sold on this plan yet so open to suggestions, but it is plan A.

5. Carbon-core plastic honeycomb 1" sheets for deck. 1 layer of 1708 on the bottom and 2 on the top tabbing into hull sides.
5.a Hatches cut in for access to tank fittings on both ends and batteries.
5.b. Coosa epoxied in area under the seats to support pedestal mounts.

6. Bulkheads made with the 1" honeycomb tabbed to the existing dash, hullsides and stringers but not sole to avoid hard spots.

7. Cuddy area to remain original but tabbed to hullsides rather than epoxied.

8. Motor splashwell and seats area made with the honeycomb. 25" in from transom to allow motor to full tilt up.
8.a. Splash area will have a panel at 45 degree angle up from transom 19.5" up from the deck still allowing full tilt. The angled panel is to allow bilge access.
8.b. Seating on either side of splashwell. Seat height will be around 14" to allow a 5" or so backrest and hip support on each side. Seats will be about 18" deep and 19" wide. This area is plan B for the batteries. I would prefer to keep these areas under the seats open for storage or coolers or one of each.
8.c The vertical panel in front of the seats and splashwell will have a hatch in the center for bilge access. The opening should be about 18" high and 24" wide to reach down in under the 45 degree panel between the seats in front of the motor.
8.d Should the two inner stringers not be fully deck height to allow access to the transom between the outer and inner stringers? Thinking it might be necessary for trim tab installation.

That's it for questions for now I think. I will be ordering the honeycomb, 1708 and epoxy soon. I already have the Coosa. This should get me started and keep me busy for a while. Thanks for any feedback offered.

[JBASS02]

My one piece of feed back would be to rethink the 1708. I started my rebuild using 1708 with epoxy, a few months ago I ordered some 1400 (1700 would be the same just heavier) it is sooo much easier to wet out and work with. It bends around corner easier, two layers end up being the same thickness as 1708 and stronger. I also end up using less epoxy too.

[FLexpat]

Rethink the transom; 3 layers of 3/4 Coosa with glass means your transom will end up being 2-1/2 to 2-3/4 thick and that doesn't work for some motors.
I would also suggest going at it from the inside.
Ditto comment on 1708 - no mat is a better choice in most locations. I wish I could shave the mat off the glass I have.
And Coosa is great in compression (like for through bolting) but it does not hold screws super well unless you put some sort of insert in (seat pedestals)

[dirtwheelsfl]

Alot to go over right off the bat!

1. Start with the transom. Two sheets of 3/4 is standard, skip the glass between and just use epoxy/cabosil.

2. Sounds good

3. Sounds pretty far aft...

4. Cross that bridge later

5. Sounds good. Probably need an extra rib over fuel tank on underside.

6.Yes but tab everything

7. yes

8. A: splashwell sounds huge unless im misinderstanding. Shouldnt need even half of that distance to tilt up.

D: ideally yes full height. Depending on what tabs, you may be able to snake wire thru limber holes. Hydraulic have to get creative

[Locke N Load]

Thanks guys.
My assumption on the transom thickness is for the goal of having it 3" thick. This is not the case? The Merc 150 4S motor drawing shows 3.1" for transom thickness and the Zuke 140 is 3.0. Are those the maximums possible? I will go with the residents here with the actual experience. Saves me a sheet of Coosa for other applications then! I will skip the glass in between sheets too since that was solely to gain thickness.

1708 vs. 17 oz. cloth debate. I know it will require more resin for the 1708. I have read 1708 is easier to work with, especially for a noob, than the 1700 since it is stitched and holds it form better. I do have some practice materials to play with. I just haven't yet. I will before making that decision then. Also, the 1708 being thicker allows for less layers to get that corrugated cardboard effect for strength. Just go with more 1700 layers instead?

My description of the splashwell sucks, but I cannot figure out how to explain it. Again the drawings for the motor show distances of 23.7" and 22.5" respectively for clearance from the transom when the motors get fully tilted up. I wanted to give it a little extra space so the cowling won't touch so figured 25" for the front splashwell wall from the transom. Pictures would be worth a thousand words here so maybe I will do a mockup with cardboard to show what I am thinking.

I could slide the gas tank as far forward as possible and put the batteries elsewhere. Is that a better plan? I figured the weight distribution would be the same either way, but it could be better to have the batteries forward away from water at the transom. The tank is built and sitting between the stringers now, but not secured yet.

I do appreciate all the comments and suggestions and want to get this as close to right the first time as I can. It would suck to go through the whole process for it not to ride right or realize I enclosed an area I need to be able to access and have to redo things. So lots of questions first. Measure twice, cut once.

[Locke N Load]

A quick drawing to help visualize the interior stern. Splashwell in the center with seats on either side. The double arrow pointing at the splashwell is the panel at 45 degrees coming from the transom to the top of the front of the seating/splashwell area.

[uncleboo]

I used one sheet of 1-1/2" Baltek, (similar to coosa), for my transom glassed in from the inside.

[Billsseacraft]

If you plan on using gel coat be very careful using epoxy they don't work well together. I might suggest looking into the vinyl ester resins. If you going to paint with Awlgrip or similar epoxy will be fine.

My transom is 3 3/4" coosa on my 23. Seems like a bit of overkill but I'm not concerned about bracket coming off!

Try and figure our center line (forward/aft) of your boat and start doing a weight and balance to find out how weight forward and aft will affect the way your boat sits in the water. For example we calculated on my boat that moving the fuel tank a foot or so forward really helped on keeping the boat at an attitude that looked original. However as I burn gas this advantage goes away. That why I have a cooler of beer in front of console too. Oh wait that goes away almost as fast as the fuel! My brother and I put a lot of thought into where to put scuppers I believe you want 1.5-2.5 inches above the water line when boat is full. Again figuring out where you can put weight forward really helps out.

Good Luck!

[Locke N Load]

The plan is to paint so no worries about using epoxy.

I was originally going to add a bracket. I did Capt Terry's CG calculations and had it about 8" aft I believe. Now without a bracket it is within an inch so within the margin of error for measuring or guesstimating weight. That is with the gas tank as far forward as possible and batteries near the helm. I really want to keep the batteries forward.

I am still thinking on scuppers. Criss-cross. Sidemount. Large ovals out the back under the seats. Ping pong ball. Not sure yet.

[Billsseacraft]

My batteries are roughly center line on boat maybe a few inches forward.