CS mk3 cascading hatch

[Designer]

While on my trip I got to go flying. As the hanger doors slid by each other I thought, I should revisit the cascading hatch.

 

Alan and had discussed it and it was dismissed. My main criteria was that it must not leak at highway speed in driving rain.

 

Here is what I came up with. Three hatches made of 3/8" ply. Each one has one has cleats front and back that stiffen the hatch and overlap its partner so that when it is pushed open it collects it's partner as it is pushed open or closed. 

 

The cleats will have some weather stripping which will compress against it's partner when the hatch is closed, There will be a sweeper strip of rubber or plastic on the front of each cleat that bears down on the hatch or deck below. The green piece is a coaming that surrounds the trench perimeter to keep any water out that gets by the hatches. The rails are 3/4" ply with grooves cut for the hatches to slide.

[IsZataRock]

Graham,

 

I LIKE it!  Is this the cake we can have and eat too?  Access to the forward mast and anchor well, good ventilation, ability to stand in the cabin, AND waterproof?  Oh, and not as pricey as the very sweet design that Doug worked up.  Looking forward to more details.  And, since your boat is likely to be the first one with this design to be rained on, let us know if the weather stripping/combing configuration works as well as we hope.

 

Hal

[tom151]

Alan and had discussed it and it was dismissed. My main criteria was that it must not leak at highway speed in driving rain.

 

Here is what I came up with. Three hatches made of 3/8" ply. Each one has one has cleats front and back that stiffen the hatch and overlap its partner so that when it is pushed open it collects it's partner as it is pushed open or closed. 

 

The cleats will have some weather stripping which will compress against it's partner when the hatch is closed, There will be a sweeper strip of rubber or plastic on the front of each cleat that bears down on the hatch or deck below. The green piece is a coaming that surrounds the trench perimeter to keep any water out that gets by the hatches. The rails are 3/4" ply with grooves cut for the hatches to slide.

 

Let me nit-pick a little...

 

As you know, water will really pool up between the siderails ahead of the hatches in a heavy rain (and much more so during trailering) , consider adding "serious" limber holes in the side rails ahead of the coaming at the front of the trench (almost as large as typical handrails).

 

With the sliding sequence of hatches shown in the sketches (e.g. aft-most in the top-most position... fwd-most in the bottom position) there ends up being three (3) sweeper strips vulnerable to leaking.  If you reverse that so the aft-most section is on the lowest track (and slides 'under' the hatch section ahead of it) then you eliminate the sweeper strips needed between overlap between hatch 1 and hatch 2, and similarly the sweeper strip between hatch 2 and hatch 3.  Of course there might be a bit more too it than that    Not sure but you may also be able to make the fwd 'twartships hatch coaming solid between the rails (instead of having a gutter (water channel) running along the full length of the side rails.  Don't know how clear that is, but hope the basic idea got across.

 

Of course it ain't that easy, and there are lots of details involved...

 

I really like that by dividing the hatchway into three it brings the crew so much close to the mast.

 

Can't tell from the dwgs, but If there isn't one, consider adding a sturdy standing/stepping location inside the boat (with the hatches most forward) in a position that allows the crew to stand with their waist/hips just at the level of the coaming - standing in a hatchway so that you're well braced without using hands is quite helpful if you need to fiddle with the sail in the rough stuff.

 

Cheers,

TomH

[Steve W]

I like it, but it seems like it would need to be built with extreme precision to be watertight. It will be interesting to see all of the ideas that take shape as all these Mark III's start to near completion. I really like the idea of a walk through type hatch and I worry about handling lines during docking and anchoring if it isn't easy to get to the front of the cabin. This looks to solve that by keeping the cabin open its whole length. It would be interesting to hear Doug chime in with his experience.

 

I think Tom's idea of having a step falls in line with my plan to make a floorboard between the bunks that lifts up into a table below. I think that step down is a big one and an invitation to a twisted ankle. I plan to have a fold up step (or battery box) and the floorboards.

[Pete McCrary]

I, too, like Graham's cascading hatches.  From the photos, it looks like he has in mind flat surfaces for each hatch.  That would ease the perfection needed for a waterproof and easy sliding assembly.  It will still need careful workmanship.  I second Tom's suggestion that the limber holes be "seriously" large enough for heavy drenching in high winds.  But all precautions won't keep all the water out if you're driving thru a rain squall.  Best hope will be to at least try to channel what water comes in down to the bilges without soaking everything in the cabin.

 

I also liked Tom's suggestion of having the aft hatches sliding forward under the others.  I've sketched a conceptual design that might be worth considering.  With most of the wind nearly always from fore to aft, such a design would seem easier to waterproof.  Fabrication seems easy enough with the side coamings cut from solid wood with a set of dado blades.  All other joinery is flat and at right angles -- except for the coaming at the forward end of the companionway.  And I would think some simple short pieces of weather stripping between the sides of the hatches (1&2 and 2&3) at the aft end of the wider hatch would keep out most rainwater trying to enter aft to forward that might be caused by a "back draft" when on the highway (or parked on shore or in a slip).  A little bee's wax or silicon lub would keep them sliding nicely.

 

Concerning the limber holes.  For boats that mostly live on a trailer, they need to be easily accessed and sized so they may be cleaned out frequently.  I have to cope with substantial pollen and tree debris which I find seems to clog up even very large limber holes.

 

I haven't thought about the door to the companionway and its proper interface with the aft most hatch (and its stowage when not used to close the companionway).

 

From Graham and fellow builders -- I'd welcome critical comments and suggestions. 

Cascading Hatches.pdf

[Hirilonde]

Are you thinking cabin doors or the possibility of weather boards?  Either way, I would have them close under the hatch, not behind/over.  Doors are convenient, but usually in the way on small boats, even on larger ones.  With weather boards you can use 2 or 3 depending on storage space.  I found that while cruising for up to 2 weeks I removed my weather boards, stored them, then didn't see them again until the end.  But I had a dodger over the companionway.  I would bet though that in a period of nice weather that you may find them not coming out at all.

[Pete McCrary]

Yes, I too, put away my weather boards. And on my catboat the doors were lifted off their hinges and stowed. But I worried about the warnings by safety advocates that when sailing, they should be in-place protecting the cabin from ingress of massive amounts of water in case of a knockdown. At 81, you could say that I'm a cautious solo sailor, and I avoid harsh weather. Maybe the cs20.3, when on its beams, the leeward edge of the companionway is above the knock-down water line? Did anyone notice that when Graham did the "righting" demonstration?

I would want the doors to be easily removed (and replaced) and also have a dedicated place for convenient stowage.

A further comment on the hatch design concept. Being flat and square keeps weight down and is far easier to fabricate. However, being flat w/o any crown -- they probably are not strong enough for rough treatment (like walking on them). Maybe the tops should have little warnings signs (like on some parts of aircraft) saying "NO STEP"?

A modest request: It would be appreciated if someone could identify [for me] the member who is building the Core Sound 20 Mk 3, #4.

[ecgossett]

How about weather boards / companionway hatch size that allows the boards to double as bunk boards? This also gives you potentially more storage for bulky things like sails, dry suits, survival suits underneath, without stepping on them.

[Steve W]

I think this is going to fun to watch all the possibilities evolve. My plan is to build it and then make a cardboard top and then just try and hash is out. One thing that I am not sure of on Core sound rigging is ho much can be done from the cockpit. It sure seems that these boats can be reefed, sails hoisted, etc. without going forward. What I worry about then is just going forward for docking, anchoring, etc.   Jay (CS20.3 #2) is putting a conventional hatch forward, and that might not be a bad way to go, the more I think about it. I think his is offset, but I could be wrong. 

 

I do think a completely open top offers a nice place to stand when not under way. I can't wait until I am at the stage where I need to make a decision. 

[Chick Ludwig]

I'm going with a forward hatch rather than tunnel. I plan on anchoring from there too. Not so sure about docking. All sail handling can be done from the cockpit. I like things simple, and the cascade or other type of "tunnel cover" is kinda worrisome for me. Too much to fiddle with.

 

I do plan to make the forward hatch slide aft rather than lift. I want to be able to open it with the mast laying down.

[Pete McCrary]

Edward, thanks for the idea. Hadn't thought of that. Great idea! I've made such boards to cover part of a cockpit to expand the width of seats into bunks. But also so that I could deploy a beach style chair to relax in at the end of the day. And I've used the beach chair when motoring a transit in a calm or adverse wind & tide. I just love "two-for s." Your idea is at no cost of stowage space.

[Pete McCrary]

Steve & Chick,

I'm pretty set on the trench style companionway. Combined with a tent canopy (no designed concept yet*), it will give you walking-around headroom. A hughe advantage for comfort.

Last night I in near-sleep I realized a problem with my hatch design concept. There needs to be a way to hold down the hatches so that they won't bounce off when trailer hits a "hump" on the highway OR a big wake or wave on the water OR a knockdown. Later, I'll sketch a concept for that. Probably won't be much trouble.

* Has anyone tried their hand at conceiving an easily deployed canopy that would fairly well keep rain and dew out of the cabin and the cockpit forward of the mizzenmast?

[Steve W]

Pete, I have another idea that I want to investigate. Like you I really want to keep the trench and a tent strung over it. I think it would give some needed room in inclement weather. I was thinking along the idea of having sort of a saloon type top hatch, hinged along both sides with a ridge attached to one side that would cover the lower side and create a good seal. By being sort of crowned it would be strong closed, and shed water easily. Open, it would lay across the forward deck sides, because the width of each "side" would only be half the trench width. Latching the forward half would be accomplished with a spring loaded pin and trip rope. With an actual matching saloon door, getting forward would be just a matter of opening the doors (The doors would lock and prevent the hatch from opening) and flipping the two halves open,  going forward. I've even fantasized about nesting a skylight and at anchor snapping a cover over the verticle sides to extend headroom and I'd be able to see out the "skylights".  I think this whole assempbly could be made very light. The key would be to make sure the hand rails along the sides were made to support the open hatch so they could be gently stepped on.

 

Incidentally, they make some really sweet plastic hinges fro just this type of application. http://www.usplastic.com/catalog/item.aspx?itemid=22757

 

This would make the weather seal along the sides really easy, creating the challenge only forward and aft. I think f the hatch was elevated just a bit (say 3/4"), a front lip and a bit of overhang aft would be sufficient.

 

One of these days I need to draw this up.

[Action Tiger]

My only interest in this thread is academic, but both Bolger and Michalak drew lots of slot tops.

The best place to start is often where someone else left off...

[Soundboats]

This hatch subject is of interest to many.  I thought I would add my "two bits" with article that I wrote for Duckworks Magazine this spring.  So here it is. 

 

My latest project is a 21 ft Sharpie for my daughter and son-in-law. Since my son-in-law is 6'3" and the cabin height is only 4 ft I decided that Phil Bolger's idea of a full-length cabin hatch was something I needed to include.

The major problem I was facing, however, was a cabin length of 7 ft. A solid 7 ft hatch would have been quite heavy and difficult to hinge along one side. I liked the ideas of Gary Blankenship I saw in Duckworks Magazine, but it still seemed a bid daunting. I had almost decided to scrap the full length hatch when I realized that the hatch does not have to be solid. What if the hatch is made of a marine vinyl cloth that can be slid along the hatch coaming? This concept has been discussed, but I have never seen anyone trying it. Well, there is always a first time, so I decided to try it. Here is a description of my first attempt, and I think it will work.

 

The basic structure is marine grade vinyl fabric stretched onto wood ribs with the ribs having small blocks that ride in aluminum U-channels that are attached to the outside of the coaming (Figure 1).

Figure 1

Figure 2 shows a rib made out of 1x3" lumber with ¾ " square wood extending down the sides. The slides are 1.5 inches wide and can be any height that is a little less than the opening of the aluminum channel. I used some ¾" x 1.5" PVC trim boards I bought at Home Depot.

Figure 2

I use PVC to keep the sliding friction to a minimum (Figure 4). The picture also shows the ¼ inch shim I used to set the exact distance as I attached the slide.

Figure 3

I cut the vinyl width so it was exactly the distance along the outside of the rib, plus 2" for hems (1" on each side). In my case that was 23.5 + 2" or 25.5". Then I hemmed the sides with 1" hems. This width gave me enough material so the truss head screws I used to attach the vinyl to the ribs would go through 2 layers of material.

To simplify the process of attaching the vinyl to the ribs, I used double sided, exterior grade, foam tape. I used the 3-M product since past experience has shown that this works best for me. Other brands such as Harbor Freight, don't last long in the harsh marine environment. I put the tape first on each rib and then taped the rib to the vinyl along lines I had drawn. The truss head screws were used to permanently fix the vinyl to the ribs (Figure 5).

Figure 4

The final step was to attach a gate latch to the outermost ribs (forward and aft) on each side. These latches had a ¼" rod that could slide into predrilled holes in the coaming. The cover is now in place and can be opened from either the bow or the stern.

The vinyl and ribs can be compressed to about 1 ft, so actually this in not a hatch that spans the entire cabin. However, it can be opened from either end and will not interfere with the handling of the mainsail.

I have not yet finished the boat, so don't have a discussion of how it actually works in reality. However, the initial set-up and testing suggest it will work well. The hatch can be opened while under-way.

I bought the vinyl at Rochford supply. They often have the best prices. They have different grades and colors so you can pick and choose what you want.

 

 

 

P.S. The boat has been in the water now and the hatch is very effective at keeping the water out whether rain or spray. 

[IsZataRock]

I'm building a CS17, Mk 3 and struggled with the hatch question for some time before deciding to go with a forward hatch, companionway hatch, and a "companionway hatch" rather than drop boards.  I think my hatches will work fine but final testing awaits getting my boat on the water.  

 

All hatches are lids with 1" edges.  All are held in place with two, transverse bungie cords on the inside (except on external cord to be used on the companionway hatch to seal it when outside cabin). All will have foam seals.  Presumably, if all are in place, the boat can be rolled and no water will enter the cabin.  The top hatches are curved to match the cabin top with 3/4 x 1" ribs which, with the edge cleats, keeps the curve across the hatch.  The "vertical" hatch fits under the back edge of the companionway top hatch.

 

These weren't particularly difficult to build, look pretty decent, and are likely to be more waterproof than alternatives I've read about.  We'll see how easy they are to use

 

I hope to post some pictures later, if anyone is interested.

 

By the way, I would be interested in people's experience with using the forward hatch for anchoring when single handed.  I can't see running back and forth from the motor to the foredeck.  I plan to deploy my anchor from the cockpit.  I'll use a line to haul my anchor line aft for anchor recovery.  Could be I seldom open the forward hatch unless anchored.

 

Hal

CS 17, Mk 3, Hull #5

[Jknight611]

Hal, if there ain't a photo, it didn't happen!  Sure would like to see some photos.  I admit I am a fan of doing R&D (research and duplicate)!  Waiting to see Chick's forward hatch as well.  On my build I have ordered some door tracks that are used on power boats for those huge glass cockpit doors.  I am investigating using them for a aft sliding forward hatch.  I have deck beams and I hope to anchor the extrusions to the beams. Originally was going to install my forward hatch offset starboard but after I installed the mast and lowered the mast I realize even offset, for the hatch to be useable sized the mast is in the way, (my personal beam issues). I guess this will be my 3rd change on the forward hatch.  I built cabin doors on lift off hinges, the doors are small and easy to store in the quarter berth.  The main hatch is hinged forward because I  want to add a dodger patterned after the one Graham rendered on his 17 .3.  It seems to me that a sliding main hatch with a dodger would involve too much "stuff" on the rather small coach top.   

 

This year's MessAbout should be the year of the MKIIIs.

[Chick Ludwig]

I, too, plan to anchor from the forward hatch. I don't see any problems with it. I may plan on rigging it to run the anchor rode to the cockpit. The trick is to get the anchor "on deck". I always use a short bow sprit for my anchor and leave it (the anchor) on the sprit, but I still have to be able to reach it to pull it onto the sprit, or deploy it. There is a tilting, self deploying and retrieving anchor roller available that would allow doing it from the cockpit. I'd think that there would be one available the right size cheaper than this one, but you can get the idea from it. http://www.fisheriessupply.com/sea-dog-line-pivoting-medium-bow-roller-328068

[Steve W]

This sure is going to be interesting. I am not anywhere near you guys progress and I sure hope you all figure this out before I get that far. I won't be doing much until October, but then it will be my focus over the winter. I had a change in my work culture with the sad loss of an employee and I've been working long hours. 

 

I do think that deployment needs to be either from the safety of the hatch, feet below, or from the cockpit. I think going up on the deck, as high as you would be could be problematic with the light weight of these boats. I'm tall and lanky, so I may be able to reach the anchor around the forward mast, which is my hope. I would like to keep the anchor and it's mud up forward. You guys that are lucky enough to anchor in sand and haul up a clean anchor need to experience the clingy clay we have around here. I ran into a similar goop up in Maine.

 

Chick, those anchor rollers are sweet for deployment, but retrieval can be an adventure on boats without a big overhang or a bowsprit. when the anchor leaves the water in any wave conditions, it can become quite lively, crashing into all kinds of stuff, so take that into consideration.

 

Take Care,

Steve

[Chick Ludwig]

Steve, here is the set-up on my Mk-2 for the anchor. It was not self deploying. I'd go forward on the side decks using the cabin as support. If it was rough, I'd sit on the cabin and scoot forward, then kneel on the fore deck with the main mast as support. With the Mk-3, you don't have the security of the trunk cabin to lean/scoot against. I have cruised on boats with a forward hatch and did my anchor work while standing in it. I think when you get to that point, you'll find that it's a "non-issue". The anchor roller-on-a-spit" makes the difference. Be sure that you have a way to secure that the anchor won't come loose in a seaway.

http://messing-about.com/forums/uploads/monthly_10_2012/post-1823-0-08758600-1351703543_thumb.jpg

 

If you go to my building thread, you can see it in a bigger picture. You'll have to scroll to find it. http://messing-about.com/forums/topic/8080-cs20-mk2/?hl=%2Bcs-20+%2Bmark   It's on page 3.