Waterline Marking

[jimschofield]

Hi fellow builders,

I'm nearing the end of the dreaded fairing process and hope to put on a primer coat soon. 

So thank you Joe Viveash for the idea of making a cradle, shaped to the hull before I turn it and I will also mark a center line for the keel and rudder positions.

But is there anything else I could do before I turn ?

Would it be an easy time to mark the waterline for antifouling, with my laser ? If so, is the water line right on the transom edge or a bit up ?

Should I finish the skeg and bolt it on ?

Jim

[captdan]

Feb 17, 2021 23:50:05 GMT jimschofield said:

Hi fellow builders,

I'm nearing the end of the dreaded fairing process and hope to put on a primer coat soon. 

So thank you Joe Viveash for the idea of making a cradle, shaped to the hull before I turn it and I will also mark a center line for the keel and rudder positions.

But is there anything else I could do before I turn ?

Would it be an easy time to mark the waterline for antifouling, with my laser ? If so, is the water line right on the transom edge or a bit up ?

Should I finish the skeg and bolt it on ?

Jim

Hey Jim,
Fairing is so much fun huh ?

I dont have all of the answers but here are a few thoughts.

Good idea about marking the keel and rudder positions. I went a step further with the keel portion ..... I made the steel base plate for the keel complete with holes and transferred them on to the hull. I then drilled the holes through the bottom and the oak floors. This is so that when the time comes to bolt up the keel, I know it will fit up nicely and no drilling holes overhead while the keel is loose under the boat. I will credit Greg Martell with the idea of using fiberglass / epoxy inserts in those holes to prevent ANY possibility of water contacting the wood in those areas. They are chamfered on the outside of the insert and epoxy in. There is a post about his procedure here on the Forum somewhere. On my blog there is some video of the inserts and how they were installed.

Waterline : I like the idea of marking the waterline before you flip the hull. I believe I saw that Kolibri did that on the boat they are building. I think that will pay dividends down the road. I need to mark that soon on my boat but now I need to RE level the boat on the trailer to do it accurately.

Skeg: In my opinion there might not be a huge advantage to bolting that on as it can be fitted quite easily and holes drilled from the cockpit.

Stem fitting and bowsprit support: I would mark these holes while in this position. Then everything is in line from stem to stern .....

Cheers!
Captdan

[jimschofield]

Thanks Dan,

When drilling for the keel bolts, I was going to drill from inside, when flipped and make the holes in the steel plate fit those positions. If you drill from outside, how will you accurately hit the middle of each keel piece ?

I like Greg's idea about the inserts but I thought it might be simpler to drill an oversize hole, fill with epoxy and filler, then drill again to fit the bolt. West System promote that method.

Now I'm confused !!!

Jim

[captdan]

Feb 18, 2021 9:48:17 GMT jimschofield said:

Thanks Dan,

When drilling for the keel bolts, I was going to drill from inside, when flipped and make the holes in the steel plate fit those positions. If you drill from outside, how will you accurately hit the middle of each keel piece ?

I like Greg's idea about the inserts but I thought it might be simpler to drill an oversize hole, fill with epoxy and filler, then drill again to fit the bolt. West System promote that method.

Now I'm confused !!!

Jim

Hey Jim,
Yes, you can transfer the holes either way for sure. 
I just remembered that I had drilled the holes in hull and floors before I had did the fairing ......  that is how I was able to be accurate with the location.
In terms of "making sure the holes are in the middle of each keel piece" - well, I was perpendicular with the plywood in that area where I was drilling. Its the same as if you were drilling from the inside of the boat .... you need to make sure you are perpendicular with the top of your floors.

Filling holes with thickened epoxy will work the same but honestly, this was so much easier with the inserts. 

There are so many ways to skin a cat ..... not saying my way is the best for everyone.
Cheers,
Dan

[jimschofield]

Thanks Dan,

I love how we all can do the same task several ways, takes the boredom out of it !

Jim

[martellmarine]

Feb 17, 2021 23:50:05 GMT jimschofield said:

Would it be an easy time to mark the waterline for antifouling, with my laser ? If so, is the water line right on the transom edge or a bit up ?

Jim

Great idea to mark the waterline. A couple of things to consider...

1. The displacement of the boat at the design waterline is calculated at 1145kg. Each centimetre of immersion adds approx 75kgs. 

2. Not sure if there has been any discussion about estimated heavy ships displacement (think loaded up for a CG580 event), but that estimated weight would depress the boat on its lines. 

3. Boot top allowance. This (kind of) is the additional anti foul applied to the boat above the actual water line to stop growth of algae and general discolouration of the topside paint. 50mm is a good starting point.

4. The combination of added weight and boot top allowance will be the line that you want to mark.

[captdan]

Feb 19, 2021 4:15:21 GMT martellmarine said:

Feb 17, 2021 23:50:05 GMT jimschofield said:

Would it be an easy time to mark the waterline for antifouling, with my laser ? If so, is the water line right on the transom edge or a bit up ?

Jim

Great idea to mark the waterline. A couple of things to consider...

1. The displacement of the boat at the design waterline is calculated at 1145kg. Each centimetre of immersion adds approx 75kgs. 

2. Not sure if there has been any discussion about estimated heavy ships displacement (think loaded up for a CG580 event), but that estimated weight would depress the boat on its lines. 

3. Boot top allowance. This (kind of) is the additional anti foul applied to the boat above the actual water line to stop growth of algae and general discolouration of the topside paint. 50mm is a good starting point.

4. The combination of added weight and boot top allowance will be the line that you want to mark.

Hey Greg,
The only thing that I saw in regards to "heavy displacement" is in the Specification area of the website where Don had sketched a blue line that looks to be 60cm above the DWL. I will try to attach the photo below.
I like your idea of the some sort of antifoul above the DWL - I remember seeing that Interlux had some sort of product for that. 
www.interlux.com/en/us/boat-paint/topcoat-finish/brightside-boottop-striping-enamel

[Admin]

Where to put your waterline....from TREKKA's experience I would absolutely make it a minimum of 5cm up the transom...and if your staying in the water in a dirty water port I would go to 6 or 7 ...always better to be higher than lower ...have fun!!!