And so it begins

[25yearslater]

Yeah, yeah, hurray. My Alumaprep 33 and Alodine 1201 purchased from Aircraft Spruce and Specialty are here so more soon I will be making my mast golden color again without paint. This is a chromate conversion coating that protects metal with a micro thin coating. It can also be used as a preparation prior to painting so if everything goes in the dumper it will be easy to paint.

 

[Panta Rei]

o where did all the time go? I thought you had posted something about the hull liner trim a few weeks ago. I can't find it anywhere in your old posts.
I'm installing hull liner. I like the look of the end trim pcs you made. I don't recall what you covered to make the pcs, it seemed like the perfect thickness.

by the way, removing and installing hull liner is one of the easiest items on my project list. It's surprising, since you see so many used boats for sale with grungy hull liner. Something that could be corrected in an afternoon.

 

[25yearslater]

Hi Todd. I used the same 1/4 inch Volara foam I used for the hull itself. Page 21 gives the description.

 

[25yearslater]

Well the Alodine went for poop. Didn't turn anything golden color despite cleaning with Alumaprep 33. Oh well soon as the million and six holes are welded up it's going to get painted. At least the Alumaprep etches the hell out of an aluminum mast which should be just the ticket for paint adhesion. And take care of these mast things. I priced out a replacement extrusion from Rigrite. The original oval has been replaced with a 'more aerodynamic' version that would require a new masthead to fit. The mast only (no hardware) goes for the low low price of 2994.00. As for the aerodynamics, it's a friggin sailboat for crying out loud.

 

[jibes138]

don't underestimate the drag created by a round rod in the wind. On racing boats even the rigging is now airfoil shaped. Just a round piece of rigging wire creates a tremendous amount of drag in a say 30 mph wind. I'm no aerodynamics expert but took a course with a guy that was and ran some experiments in assorted wind tunnels measuring drag on assorted shapes. A round shape is awful for drag creation because of separation of the air stream and the vortices created on the back side of the object as the two streams mix back together.

 

[25yearslater]

That's interesting jibes. The original rigrite RR8 has been discontinued and the Spartan CD-4 took it's place. The rigrite has the extended sailtrack on the aft edge and the Spartan has it contained withing the oval section. I believe it has something to do with laminar flow onto the main perhaps. I also wonder is there some handling difference that would be noticable as opposed to altering boat speed or something to that respect. That would make sense for the newer design. Possibly something as simple as righting moment. Dunno?

 

[jibes138]

I looked on rig rite to see what you meant. The Spartan Design looks simpler and cheaper to produce with less metal. I think the space behind the mast where the track is will be insignificant because either shape will likely have a turbulent region immediately behind the spar, even though neither is very aerodynamic. The gap created by the sail slides means a small amount of low pressure and high pressure air will be trying to mix there and will create turbulence. If the track had a boltrope it would keep the two air streams separated. The leech and top of the sail have the same issue, air at two different pressures is mixing and creates a turbulent region that results in drag. Airplanes solved the wing tip problem by adding tiplets to the end of the wing to prevent the mixing there. Tough to do that on a sail.

 

[jibes138]

See what the difference is in weight of each spar. Weight aloft will have a very big effect on handling and performance. Given the height of the mast the heeling moment is impacted by the weight and the CG, my old sailmaker used to not put sunbrella suncovers on sails to try to keep wight aloft down, I told him it didn't matter to me but he was a purist.
I want you to try something today. Take a round object like a piece of wood rod and drive down the street at 30 miles an hour with it sticking out of the window and see how hard it is to hold it. The do the same thing with an airfoil shaped rod, you'll get instant feedback on the effect of drag on a round rod. If you are in a 25 MPH wind on your boat and doing 5 knots to windward the apparent wind will be 30 knots. Now take that drag from the round rod and add it up over all the rigging on your boat and you'll see the effect of drag is enormous. In our windtunnel experiments we were using different shapes to try to reduce drag and improve mixing of the airstreams, things that looked like corrugate cardboard for instance. The attachment point of the object was on a force scale so we could measure changes accurately.

 

[25yearslater]

I tried the driving experiment as suggested jibes and the results were quite apparent. The mast sections cause me to wonder how to keep the boundary layer from separating at the sail luff with each type. I need to get a hold of some of my old school chums from Embry-Riddle. Maybe they could explain this shape thing and laminar flow so a management major could fully grasp the concept. It would be a shame to think it was strictly a dollar thing. There is a likelyhood I will in the next few years replace the stick as soon as the paint goes to hell so I am very curious. http://www.rigrite.com/Spars/Rig-Rite_Spars/RR-8_Mast.html http://www.rigrite.com/Spars/Spartan_Spars/cd4_mast.html
And for those curious here are the links.

 

[jibes138]

Glad I perked you up there with another mystery to solve 25 years. Advanced racing boats I have seen in Newport RI, like racing trimarans and catamarans, seem to use a mast that rotates and is airfoil shaped and has the sail on a rope in a track in the mast so laminar flow can be obtained. In our case with a fixed mast it is unlikely you will achieve much in this area without a major modification to your boat and a lot of dollars. The drag from the wire rigging is a lot and the experiment showed that. In the end once you get up to hull speed the drag probably doesn't matter much because you have the hydrodynamic forces at work keeping you from going faster. Interesting subject matter for potential research. Enjoy.

 

[25yearslater]

Gotta have something to do while I wait for April besides helping Mrs. 25 sew the curtains.

 

[rajhnsn]

Does this make a case for in-mast roller furling?

 

[jibes138]

My comments about air flows and drag are gross simplifications of an incredibly complex subject. In Don Guillette's forum there was a big discussion a while back and RichH provided a wonderful article that pretty clearly explains the aerodynamics without a lot of math. Here is the link and I hope you read it especially over the winter while the snow vortices are swirling in the back yard. You will enjoy this.
http://www.arvelgentry.com/techs/origins_of_lift.pdf

 

[jibes138]

Regarding in mast furling, you typically have the sail with a loose foot, so you are allowing high pressure air and low pressure air to mix along the bottom of the sail, from listening to an aerodynamcist at Boeing one day regarding mixing at the wing tips, I'd have to say this is a bad idea. To the extent the boom creates a barrier to mixing it is probably good to be attached there but I can't honestly say whether the boom efficiently performs this function or not. I am also not too sure about the pressure differential right at the luff of the sail to know how much an effect a small slot has at that location. It is probably in a very turbulent region from the disruption of air flow caused by the big bulky mast shape that it probably doesn't have much effect but I am only guessing with that comment. Perhaps an internet search would turn up something I'll give it a try.

 

[25yearslater]

Well as I await the mast welding I have been tackling the nice to have jobs. One I didn't mention earlier was the head. After much confusion I gave up and contacted Transport Canada. I received the answer that made my heart leap for joy. I was able to purchase the Thetford 550P portable unit from a local RV supplier. The good news was according to Transport Canada it only need to be fixed within the boat but may be removable for shoreside discharge. Hoo freakin ray. My phobia about cutting a hole in my new deck was slain. All I need do was purchase the hold down kit which is nothing more than a few plastic latches. The 5 gallon holding tank should be more than sufficient for the length of trips I will be taking before service is required. Lake Ontario isn't that big. The other dodad was the battery mount or lack thereof. A small board with another one attched with a few screws were it. The tabbing on the factory board had delaminated which allowed the removal with only the smallest tug. Let's play Russian Roulette with 60 pound batteries being tossed about till they punch a hole through the side. A quick set of measurements revealed the only practicle area was in line under the quarter berth. Whipping up a new board with dadoed edging seemed a better option. I coated the whole shebang with epoxy that I added some white coloring agent ( I got it why not use it ) and let it cure. Screwing through from the engine side and retabbing to the hull yielded a super secure tray. With a few teak cleats and a few hold downs and the batteries will be secure. Besides that it just looks nicer down in there.

 

[bria46]

I used a Seafit battery hold down tray purchased at West Marine

 

[25yearslater]

Notice anything different? To do: Handrails, Water system, Batteries, Paint bottom, Lifelines, Fore and aft stays, Paint or reanodize mast and boom. Call for truck, go sailing. Just short of 2 years and there she is. Damn pretty ain't she? :dance: :wow:

 

[jibes138]

why so many winches? is the boat set up for a spinaker? do you have one and all the stuff needed to fly it?

 

[rajhnsn]

looks better than new!

 

[jibes138]

25, The boat looks amazing! Your tenacity is commendable. Have you found your next project boat yet? Most folks look to move up to the next bigger size right about the time they buy their boat. Please take my advice, a 25 or 27 is just right, you will use it more and it is easy to single hand and low cost to maintain (comparatively). Shallow draft gives you lots of options for cruising. Your going to love it. Great Job....a round of applause for 25yearslater!