minimum stringer height??

[flatcat]

whats the rule of thumb if any on stringer height?
looking to gain as much freeboard as possible on a eastporter style skiff

 

[Bill]

whats the rule of thumb if any on stringer height?
looking to gain as much freeboard as possible on a eastporter style skiff

It’s a push and pull of having the deck as low as possible for as much deck to gunnel height as possible , but you also want it high enough so that you don’t take on water thru the scuppers while it’s loaded up. It also has to have pitch fore to aft to make it self bailing .. that’s why an accurate waterline is everything when building a boat , especially when you also have to account for head room and a 12” minimum spill over for your inboard exhaust ..

 

[kehoff]

Is it really supposed to be 12 inch spillover on the exhaust ?

 

[flatcat]

I assume also that the higher the deck the more rugged (less flexible) the hull would be especially if its all open like a skiff

 

[leaky]

Is it really supposed to be 12 inch spillover on the exhaust ?

By no means do I claim to know much about this stuff but I had to go digging through it for my boat.

I've read 12 inches, 15 inches, seen it measured at the top & bottom of the riser in different diagrams, but yeah that's the minimum ballpark you see referenced and if you read SBMAR there is some commentary there about it being a bare minimum.

A true waterlift situation, ie where you can even have an engine mounted below the waterline, is totally possible too but there is still some spec on drop down to the top of the waterlift water level. Again, do not claim to know much, just citing what is published out there.

Designing a Marine Exhaust System

Designing a Marine Exhaust System

www.sbmar.com

 

[leaky]

As far as OP's question - freeboard to me means from waterline to where the water would roll into the boat, ie how much hull exists above the waterline. Although as you load a boat up this changes some, mostly it's a matter of the sheer - how tall the hull is designed (ie 6 inches worth of weight is a shit ton of weight for a given boat, while one otherwise similar hull to another can easily be 6 inches +/- freeboard wise).

Cockpit depth is a different consideration where the deck height comes into play.

Then a self bailing deck adds a different set of considerations where you are balancing cockpit depth, and headroom, against height above the waterline, and you need pitch to assure the water actually rolls to the stern and leaves the boat (assuming your drains/scuppers are on the transom)..

On a skiff, keep in mind you really do not need a self bailing deck to begin with, bilge pumps can get the job done just fine and then you need not worry about all this stuff. It would need to be a stout boat under 20 feet for me to consider building it with a self bailing deck, ie lots of freeboard so the deck can be set adequately tall...

But with a boat on a trailer, the nice thing is you can easily enough put it in the water, see how it sits - use objects like concrete blocks or drums of water placed to approximate the weight of what you plan to add, and witness the waterline if you want.

 

[kapnd]

whats the rule of thumb if any on stringer height?
looking to gain as much freeboard as possible on a eastporter style skiff

It’s not a rule of thumb, it’s an engineering calculation that requires very specific data.

 

[Diesel Jerry]

It’s not a rule of thumb, it’s an engineering calculation that requires very specific data.

Negative. You can set deck height to what ever you want. I put my deck low in my Eastporter removing the scuppers. It’s no longer self bailing and dependent on bilge pumps.
I went this route due to my kids are small and wanted to keep them in the boat. Also my boat will probably live on a trailer and not be left out on a moring unattended for lengths of time.

 

[Genius]

Is it really supposed to be 12 inch spillover on the exhaust ?

Yup. The most important and often ignored safety item for your engine.

 

[fordy]

My 22 foot boat has 7"-9" tall stringers. Just high enough to be a couple inches above the waterline.

 

[MAArcher]

Like Leaky said, my understanding is that freeboard is the distance between the waterline and the lowest point of the shearline, so stringer height has no bearing on freeboard. I think what you're referring too is just called "gunnel height" and is the distance from the top of the gunnels to the sole/floor/lower deck.

Why do you want to increase gunnel height? If it was me, I'd be looking to bump up the stringer height and raise the deck to improve self-bailing and stiffen up a somewhat flimsy hull. I wouldn't go to 2x4's to gain a couple inches in gunnel hight. I only had an Eastporter for a short time but I think it was a bit flimsy and taller stringers and/or more glass might benefit.

If I wanted higher gunnels to keep kids or dog in the boat I'd add a railing or what I think is referred to as a "washrail" like this forum member has on his Leblanc, the vertical board surrounding the aft deck:




I see "washrails" like that often added to Novi style boats that had low sweeping shearlines to accommodate working at the waters surface but if the boats no longer used for that adding a washrail keeps water out and occupants in. The "Hard Merchandise" on Wicked Tuna was modified like this.

You could also contact Brice Boatworks Brice Boatworks. He has the Eastporter mold and has built some so he might be able to steer you in the right direction.

 

[flatcat]

not a fan of high wash rails. they may look OK if its just on a small section after the cabin which makes them blend in better, but most of or all the way around on an open skiff most likely not
the forward third of my hull the height is fine, I'll have to look around and maybe get some ideas
I plan on no scuppers so maybe I'll just drop it real low and add a couple knee braces if needed but would rather not

 

[Diesel Jerry]

Each to their own on raising the shear or lowering the deck. No wrong way. I used 1/2 coosa for three longitudals that come all the way to the deck. Maybe 4” tall aft and increasing as the deck pitched up. The boat is more solid than when it arrived, and I stress tested the hell out of the hull, deck, and stringers putting it back on the trailer.

 

[c1steve]

I would keep the deck high, and add a coaming board for more cockpit depth.