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Re: FS19 in Sherwood, OR

Posted: Tue Apr 06, 2021 6:12 am
by fallguy1000
I am not familiar with Mertens allowing the move of the transverse frames to that degree. Most of the time, the glassing of the inside skin requires extra glass to make the change you suggest. But it may be within limits. Only the designer can say yes. Or he may say add a layer of 1700 in the tank area..

The rest of the plan seems fine. Personally, I'd be a little careful about allowing enough space for tank expansion so the chase isn't noisy on the tank in warm weather. And with batteries above a tank compartment, I'd be inclined to vent the battery box and avoid mechanical switches that may spark. I don't believe batteries are NOT allowed above a fuel tank under abyc rules, but a fuel system component is not allowed above a battery, so your fuel lines cannot run above the batteries.

Re: FS19 in Sherwood, OR

Posted: Tue Apr 06, 2021 6:24 am
by Dan_Smullen
Turning the chase tubes up 90 degrees within the ~3” of clearance between the tank and the sole may be tight. Unless the console will be wide enough to capture the open end of the tube, outboard of the stringer, it’s hard to see a different configuration. I too planned for 3” of clearance, but wound up with a little less than 2-3/4”.

What’s the plan for bedding the tank?

I had resigned to only add foam that were completely sealed, therefore no compartment with a chase running through it, due to lack of confidence sealing the penetrations, but I’ve since gotten over that. Popular opinion is such that thickened epoxy will adhere to scuffed /flame treated pvc sufficiently to seal the penetrations.

Re: FS19 in Sherwood, OR

Posted: Wed Apr 07, 2021 10:26 am
by Scrappy
fallguy1000 wrote: Tue Apr 06, 2021 6:12 am I am not familiar with Mertens allowing the move of the transverse frames to that degree. Most of the time, the glassing of the inside skin requires extra glass to make the change you suggest. But it may be within limits. Only the designer can say yes. Or he may say add a layer of 1700 in the tank area..

The rest of the plan seems fine. Personally, I'd be a little careful about allowing enough space for tank expansion so the chase isn't noisy on the tank in warm weather. And with batteries above a tank compartment, I'd be inclined to vent the battery box and avoid mechanical switches that may spark. I don't believe batteries are NOT allowed above a fuel tank under abyc rules, but a fuel system component is not allowed above a battery, so your fuel lines cannot run above the batteries.
Thanks Fallguy, I’ll see if I can get an answer on the frame movement from Jacques. Still playing with the final dimensions, maybe I can shorten by a foot to minimize the displacement. Appreciate the tip regarding the expansion and rattling chase tubes. Hadn’t thought about that.

Re: FS19 in Sherwood, OR

Posted: Wed Apr 07, 2021 10:43 am
by Scrappy
Dan_Smullen wrote: Tue Apr 06, 2021 6:24 am Turning the chase tubes up 90 degrees within the ~3” of clearance between the tank and the sole may be tight. Unless the console will be wide enough to capture the open end of the tube, outboard of the stringer, it’s hard to see a different configuration. I too planned for 3” of clearance, but wound up with a little less than 2-3/4”.

What’s the plan for bedding the tank?

I had resigned to only add foam that were completely sealed, therefore no compartment with a chase running through it, due to lack of confidence sealing the penetrations, but I’ve since gotten over that. Popular opinion is such that thickened epoxy will adhere to scuffed /flame treated pvc sufficiently to seal the penetrations.
Thanks Dan, I’ll be sure to do some testing with the chase tubes before I commit to the tank size. I don’t think the console will extend beyond the stringer but that would make things easier.

For bedding the tank I planned to bond reinforced plastic strips to the bottom of the tank and then bond that to the reinforced hull. It is a method recommended by the tank supplier, adopted from a book written by David Pascoe. But still learning and open to suggestions.

Is thickened epoxy preferred over 5200 to seal the chase tubes through the stringer and frames? Also if I run the fuel fill, vent, and pickup lines before I put the sole down is there any reason for chase tube? I suppose I’d need them in the areas where I plan to foam in case of needing to replace them later.

Re: FS19 in Sherwood, OR

Posted: Wed Apr 07, 2021 4:16 pm
by Dan_Smullen
Scrappy wrote: Wed Apr 07, 2021 10:43 am
For bedding the tank I planned to bond reinforced plastic strips to the bottom of the tank and then bond that to the reinforced hull. It is a method recommended by the tank supplier, adopted from a book written by David Pascoe. But still learning and open to suggestions.
Bear in mind, this is my first time building a boat, but I have been fortunate to have gotten advice from experienced, professional builders. I was advised to not bed the tank on the inside of the hull, but no reinforcement was discussed. I'd trust the book you've read over advice I got. As suggested to me, I bed a fiberglass encapsulated piece of 1/2" plywood parallel to the waterline where the bottom of the stringers meet the hull, with limber holes draining to the bilge front and back. On this, between this and the tanks will be 1/4" neoprene rubber strips. I believe drainage around the tank is a important as the tank being secure. I imagine, that all of the clearance, above and below the tank, could easily eat into capacity by 20% or so. I found 2 smaller tanks was better than one large as they accounted for all required clearances without moving frames.

8168
Scrappy wrote: Wed Apr 07, 2021 10:43 am
Is thickened epoxy preferred over 5200 to seal the chase tubes through the stringer and frames? Also if I run the fuel fill, vent, and pickup lines before I put the sole down is there any reason for chase tube? I suppose I’d need them in the areas where I plan to foam in case of needing to replace them later.
I don't know, but glued in my first piece of PVC last night, but haven't checked it yet. I like the chase tubes. They protect the epoxy on the plywood and the hoses from chaffing.

Re: FS19 in Sherwood, OR

Posted: Wed Apr 07, 2021 6:13 pm
by Scrappy
Thanks Dan, good stuff and lots for me to consider.

Re: FS19 in Sherwood, OR

Posted: Wed Apr 07, 2021 8:51 pm
by Dan_Smullen
Quick update, the silica thickened epoxy around PVC is remarkably tight. Seems to be very strong.

She’s looking good flipped. Nice lines!

Re: FS19 in Sherwood, OR

Posted: Thu Apr 08, 2021 3:51 am
by OneWayTraffic
I used G-flex on flame treated UHMWPE to bond it. The little test coupon I used bonded tight enough to support my weight (83kg) on less than a square inch of plastic. I think I got better than that in reality, but I know that that is a minimum.

G-flex has more give than epoxy so doesn't pop off as easily, but UHMW is about the hardest thing to bond.

Re: FS19 in Sherwood, OR

Posted: Thu Apr 08, 2021 1:10 pm
by Scrappy
Thanks Oneway.

Re: FS19 in Sherwood, OR

Posted: Thu Apr 08, 2021 8:14 pm
by Browndog
I used a 35 Gallon V-hull tank under the sole in the FS 19 that I built.

One of the reasons I raised the sole by 1” was to provide clearance for all of the fittings and fuel hoses etc., there is very little space under the sole as designed.

I bedded the tank on neoprene strips as recommended by the tank manufacturer.

If you put a tank under the sole you will need to add another layer of Biaxial glass on the inside of the hull where the tank will rest per the building notes and the designer.

I moved the transverse frames between the stringers to accommodate the tank and left the part of the frame that was on the outside of the stringers. I also added support under the sole to stiffen the area above the tank and to accommodate mounting points for the leaning post.

In my recollection there was no room above the tank for chase tubes except for a very small one for the fuel sender wire to the gas tank fill gauge and the ground wire. My chase tubes were installed on the outside of the stringers.

My build thread includes a large number of pictures of everything I just tried to describe and would encourage you to look at the thread for whatever details that I might have forgotten about.

I would strongly recommend that you mock up a console out of cardboard before you buy any materials for it. I changed the console a few times before getting it the way we wanted. After putting the hull together, building a console is a piece of cake.

I also recommend dry fitting the sole in place before finalizing the interior design. You may find that you will want to move some stuff around or change the dimensions of the front deck and it is hard to do once the sole is glued down. I shortened the front casting deck and added a rear deck on the one I built.

Fell free to call or message me if something isn’t clear to you.

Your boat is looking good. Keep up the good work.