Skagit 20 - Alaskan Bulkhead

[Skagit Hideaway]

Well, I guess before I slap a 22" extension and 640lbs of twin outboard motors (+rigging) on the back, get further along with the new AB roof and doors/windows, and start installing everything else that is perhaps going to go into this wonder cruiser (radar, gps, radio, AIS, heading sensor, autopilot, XM weather.....would love a thermal nite vision camera for when the tide is at 3am at Cape Caution - great for spotting logs and deadheads), I should figure out where the boat's various centers of gravity are, so I can keep track of them. This looks helpful:

http://microship.com/resources/cg-weight-study.html

I'll pick up a rental, 1000lb scale in the next couple of days.

Anyone weigh their boat like this - at each end?

[Skagit Hideaway]

I took Helmar's suggestion today and cut the pilot house dash back ca. 12". What an improvement. 6" of dash now will be just enough to hide the new wiper motors, with the plotter and other stuff recessed underneith. The cuddy bulkhead moves up 12-1/2 inches to just short of the back cuddy window. Now the 400+ lbs of pilot/navigator and those of multiple batteries can be located a foot closer to the bow to help balance the weight of offshore bracket and twin outboards on the back. I haven't performed the weight test yet, but estimations using the published weight and probable distribution (optimal with 285lb single on back) indicate that balancing the new gear will not be a problem. Further, I'm thinking that 1/2" marine ply sealed with 1708 on the floor (in place of the original 1/4") plus a couple of heafty through-hull CHIRP transducers (halibut finders) will go a long way towards compensating for the cabin weight. Picts once things are trimmed up a bit more.....

Thanks Helmar!

[Lyle]

I would like to see where you mount those transducers. I am trying to figure out what way I want to go with my electronics.

[Skagit Hideaway]

This Skagit had one through the hull just North of midships, which is too far foreward IMO. I took that one out and patched the hole. The Airmar recommended location is somewhere aft of the beginning of your planing surface:

"Planing hull powerboat—Mount well aft, on or near the
centerline, and well inboard of the first set of lifting strakes
to ensure that the transducer is in contact with the water at high
speeds. The starboard side of the hull where the propeller
blades are moving downward is preferred."

I'm pretty much stuck with right next to the keel, unless I modify the trailer, which is why I found bruceb's account of the improved stability of the keel-less (aft), Skagit inboard hull so interesting.

[bruceb]

Lance-
Way back in this chain, you asked where and how many inches the keel faired into the hull. So here's the pic and the measurements. It becomes flush 5' 2" from the stern and does the transition in 5.5" . As you can see in the pic, the roller is resting just forward from the transition. The boat's been on this trailer (she's not really a trailer queen !!!!) since 1961 ! Dad showed us kids the six 100's before we went to get the trailer.....
So, in cornering, this lack of a keel in the last 5 feet allows the stern to slide smoothly, banks nicely, allowing the outboard lower unit to be the dominant rudder.
At lower planeing speeds(14-20mph), a Skagit hull with an outboard weight of 250-300lbs and a "normal" load distribution will ride on the aft 7-8 feet of the hull. Hopefully the pic I choose can illustrate this. Great idea in placing the transducer towards aft, and near the keel. I'd think that being too close to the keel might interject some air from the keel. Placement between the 1st and second air-o-glide grooves might work best.
That document on weight and moments is a keeper, super great resource.
Happy constructing !
bruceb

[Skagit Hideaway]

Bruce,

Thanks for the picts. Looks like a porpoise butt with the keel faired

You are right, I think, between the air-o-glide grooves would be better, which means I'll have to modify the trailer supports.

I like the ride Bill Roberts is getting here: http://www.duckworksmagazine.com/07/...t/image029.jpg

Gonna call you soon as the boatyard is cleaned up some.

Lance

[Skagit Hideaway]

Sorry. I mean I'm calling Chuck (Skagitguy).

The inboard hull/no keel aft: Question is, how does it handle going down the backside of a large swell/wave?

[Skagitguy]

Lance-
Way back in this chain, you asked where and how many inches the keel faired into the hull. So here's the pic and the measurements. It becomes flush 5' 2" from the stern and does the transition in 5.5" . As you can see in the pic, the roller is resting just forward from the transition. The boat's been on this trailer (she's not really a trailer queen !!!!) since 1961 ! Dad showed us kids the six 100's before we went to get the trailer.....
So, in cornering, this lack of a keel in the last 5 feet allows the stern to slide smoothly, banks nicely, allowing the outboard lower unit to be the dominant rudder.
At lower planeing speeds(14-20mph), a Skagit hull with an outboard weight of 250-300lbs and a "normal" load distribution will ride on the aft 7-8 feet of the hull. Hopefully the pic I choose can illustrate this. Great idea in placing the transducer towards aft, and near the keel. I'd think that being too close to the keel might interject some air from the keel. Placement between the 1st and second air-o-glide grooves might work best.
That document on weight and moments is a keeper, super great resource.
Happy constructing !
bruceb

Bruce, My 59 Skagit has the keel faired into the hull as well. I don't recall if i saw that on my 58 Offshore or not. My transducer placement is about the same as you said between 1st and second air-o-glide grooves and works great there as it has on other boats i have had...no problems.

[bruceb]

Lance-
Yes, on that link pic of Robert's Tyee, those are the coolest riding Skagits, imho, as the seat(s) , helm are forward, so it gets the bow down at cruise speed. Here's a shot of a 20 express trimmed up.

[bruceb]

Lance-
Yes, on that link pic of Robert's Tyee, those are the coolest riding Skagits, imho, as the seat(s) , helm are forward, so it gets the bow down at cruise speed. Here's a shot of a 20 express trimmed up.

Bruce, My 59 Skagit has the keel faired into the hull as well. I don't recall if i saw that on my 58 Offshore or not. My transducer placement is about the same as you said between 1st and second air-o-glide grooves and works great there as it has on other boats i have had...no problems.

Chuck-
Yes, your 58 offshore, Bainbridge, Scotty's old boat, had the keel all the way to the stern.

[Skagitguy]

Chuck-
Yes, your 58 offshore, Bainbridge, Scotty's old boat, had the keel all the way to the stern.

On the 59 Skagit i have two 12 gal tanks up to the bulkhead compare to the way it was before with the two 21 gal along the sides towards the stern. Seems to get up on a plan easier.....ride much better.

[Skagit Hideaway]

I filled in the transom well and have begun what will be a full width, integral hull extension (21" hull or 23-1/2" to motor mount - quazi Quintrex transom style). It will be totally composite construction, except for the 2-1/2" thick wood-cored motor mount, and I'll be extending the hull profile with the air-o-glide grooves, but probably not the keel. The Evenrude motor guy recommended the hull extension over the raised offshore bracket for twin motors on this boat. We'll sacrifice a bit of performance for the increased floatation - ca. +400lbs. Here's the first piece of 4 composite I-beams - 3/4" thick. I amost lost count of the layers of 1708, roving, and 2mm coremat, but the coremat (4) is totally saturated. One coremat layer wasn't at first, so I forced it apart with large screw drivers and a hammer, ha, ha. After 45 minutes it finally gave way - much more difficult than splitting a layer of healthy laminated plywood in a composite construct. 21 - extension 02.jpg 20 - extension 01.jpg

My Dad is still scraping the hull diligently.

[Lyle]

Here's the first piece of 4 composite I-beams - 3/4" thick. I amost lost count of the layers of 1708, roving, and 2mm coremat, but the coremat (4) is totally saturated. One coremat layer wasn't at first, so I forced it apart with large screw drivers and a hammer, ha, ha. After 45 minutes it finally gave way - much more difficult than splitting a layer of healthy laminated plywood in a composite construct.

Did you build that up and vacuum cure or did you let it air cure. I was wondering if porosity would affect the strength?

[Skagit Hideaway]

Good question. I built up 3/8" of the layer formula and then massaged/pressed (flat board/weight on top) the bubbles out of it. Before full cure, I added the second 3/8", repeating everything. It is as solid as it can be, looks to me. I just finished the second one. The four of them with tops, bottoms, and central internal brace, fillets and tabbing, will make two, 11" wide Super Stringers between the old (actually new except for the outer glass shell) and new transoms - one for each motor. Then the outer shell/swim platform goes around/on top of all that, tabbed to the hull and transom.

The mechanical bond to the existing hull bottom/sides/deck/transom: When I attached the upper windshield posts, I roughed the bare fiberglass surface of the cuddy cabin spot with 40 grit and sat each post in a thick glob of milled fiberglass/epoxy glue. After curing I discovered that one cornerpost had somehow slipped and was 1/2" out of position so I cut through all but a 3/8" square of the epoxy base and decided to test-break off the rest. Rather than break at the cut or where bonded, a 3/8" square of the cuddy cabin tore out, so if anything is going to give way, it's going to be the original fiberglass, which I'll strengthen where needed. The original transom shell had ca 80 holes drilled in it - old mounting holes (reamed), new mounting holes and 60 holes for the bolts that clamped the new plywood transom layers (one at a time - 2" total) to each other and the curve of the shell during the laminating/gluing process. With all those holes milled fiber/epoxy filled the outer shell is really through-bonded to the wood layers and the internal fiberglass shell. Additionally, a 3" long tab at the top of each of the 3/4" thick Super Stringer pieces inserts (glued) 2" into the transom (slots cut). With the weight and force of the motors/waves distributed over the entire transom and stern hull bottom and stern hull side surfaces (reinforced as well as stern deck), I'm thinking that the motors will stay attached to the boat Any thoughts anyone?

[Bflaherty]

I might have something to say after I reread these posts a few times... Definitely makes me thankful I bought an all glass inboard. No rot possible except the floor or seat frames, and both are easily replaced!