|GoBackTo 2007 Chapter Five|
|April-May, 2007||Bashing Up the Pacific Coast||Mixed|
|June-July, 2007||San Diego Hull Elongation Chronology||Mixed|
|16 July, 2007||Transom Extension||Yachties|
|19 July, 2007||Hull Extension Discussion||Yachties|
|28 July, 2007||Hull Extension Details||Yachties|
|12 September, 2007||Extended Transom Performance Assessment||Yachties|
|GoFwdTo 2007 Chapter Seven|
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17 April, 2007 - We left La Paz at the beginning of the month and are trying to sail up the coast of Baja California. Presently we're in San Juanico awaiting a weather break and (surprise) we have Internet connectivity! We've been unsuccessfully looking for a favorable weather window since leaving La Paz. The slog from Cabo San Lucas to Magdalena Bay was, uh, "interesting" - they call this the "Baja Bash": the winds are consistently strong and on the nose! We sat for a week in Mag Bay waiting for a weather change and when it came we never even made it to Abreojos. Next weather window (maybe) in five days ... it blew 25-30 knots through the anchorage yesterday, with stronger winds and high seas predicted for tomorrow. No worries, we're comfy.
30 April, 2007 - Arrived in San Diego last night. GPS says we sailed over 1000nm from Cabo San Lucas to here, all of it with wind and ugly confused seas on the nose. Boat did just fine. Nothing I say is fit to print right now. :-)
3 May, 2007 - Marina del Rey. Despite a favorable forecast, the one-day passage from San Diego to here proved to be quite bumpy (sigh). Disconcerting listening to the weather channel talking about 70mph winds in nearby mountains while we're putting in another reef in a 25-knot breeze in the middle of the night. Heading for Santa Barbara on Monday...
8 May, 2007 - Santa Barbara. Just arrived here after a nice sail from Marina del Rey, dodging ships all night long (love my AIS which shows all the ships' details on the Macintosh GPSNavX chart display). Kathy is enjoying slowly unwinding and we'll hang out here for a few days while I hopefully find a weather window to get us around Point Conception.
18 May, 2007 - Santa Barbara. We enjoy being tourists in this lovely town while waiting for the weather to settle before proceeding northwards. I'm really getting tired of seeing this repetitive forecast, which is not conducive to a pleasure sail up the coast (sigh):
"...NW WIND 20 TO 30 KT WITH FREQUENT GUSTS TO 40 KT. COMBINED SEAS 10 TO 12 FT DOMINANT PERIOD 8 SECONDS..."
Home is just a five-hour drive... :-)
21 May, 2007 - Home Temporarily. Well, we took our own advice and rented a car and came home for a short while. No sooner had we done that, when the weather forecast this week turned to: "...FRI...NW WIND 10 KT. WIND WAVES 2 FT OR LESS..." What an incredible contrast with last week! (sigh) We plan on returning to the boat in a week.
29 May, 2007 - Back in Santa Barbara. Sightseeing for a day and then a change of plans as we're taking off back down to San Diego for a haulout and surprise present for KatieKat.
1 June, 2007 - San Diego. Had a simply marvelous sail down the coast, flying the spinnaker most of the way. Plans are to haul out this coming week, paint the bottom, and (surprise) scarf on a 1-metre extension to KatieKat's transoms. See Seawind's website for photos of their new SW1000XL, which we hope to emulate.
6 June, 2007 - Home. Drove home (Los Altos Hills) again, leaving the boat in San Diego. Kathy and kitty are happy homebodies, but I'll be returning to San Diego this coming weekend to move the boat and prepare it for haulout.
12 June, 2007 - San Diego then Home Again. Returned home after a whirlwind drive down to San Diego and the haulout of KatieKat this past weekend. Left the boat in the hands of able experts, and hoping to have the stretched boat re-launched by the end of the month.
12 July, 2007 - Heading for San Diego. KatieKat has been hauled out at Driscoll's in Mission Bay for the past month undergoing the transom extension. I'm heading for San Diego tomorrow to re-launch the upgraded boat. Photos and writeup to follow soon (I hope!). The near-term plans are to keep the boat somewhere in Southern California for the next six weeks and join the Seawind Catamaran Rally at Catalina Island on August 23-26.
I flew down to San Diego on Friday the 13th(!) and re-launched the newly-extended KatieKat. In a nutshell, WOW!. Bob Dixon performed a simply marvelous transformation of KatieKat - not only does the alteration look professional in every positive sense of the word, but the fairing and gelcoat matchup is flawless! Here are some Before and After photos:
Trying to show the underwater lines. The right photo is of the Seawind Sea Ya which underwent the modification before KatieKat. That inner sidewall was eventually cut down on Sea Ya.
I had sailed up the coast from San Diego to Dana Point, where I anchored and then jumped into the water with my camera to capture some of these images.
Bob Dixon (seen here working on Sea Ya) is the master artist who executed the modification.
This photo shows the dramatic absence of turbulence in the wake left by the new transom. Alongside is the motor exhaust trail. The residue on the aft step is some mud from a critter's munchy the previous night - the new step washed itself off shortly after I snapped this photo.
This photo added 28 July, 2007:
Here's a photo excerpted from a video clip taken during our passage from Australia to New Zealand which shows the wake normally seen from KatieKat. Compare this to the photo above. Thanks Adam
So far I've barely had any wind and my initial sailing impressions are that, compared with the original, the boat is faster and gives a smoother ride in choppy conditions (I sailed through the wakes of a zillion boats right at the start of the Trans-Pac yesterday). I'll try to quantify the speed differences after I've had a chance to experience some decent winds.
I'm presently in Marina del Rey and hunting for a temporary marina berth so I can keep KatieKat in Southern California until the Seawind Rally in August.
OK, ok, you ask, so, after 25,000nm with a 33' Seawind 1000, what possessed me to stretch the boat? I've received a few emails soliciting my comments about this, so I thought I'd share my thought process with you.
The existing boat has served us extremely well for seven years, primarily as a coastal cruiser in Australia, New Zealand, and the North American West Coast, and also for a number of significant ocean passages. Loaded down with cruising gear we've usually managed to keep the anti-fouling waterline visible as a result of judicious cargo selection, the worst culprits being freshwater, books, tools, canned goods, and safety gear. Last year we addressed the water weight issue by installing a watermaker which typically allowed us to half-fill the tank and thus save 400lbs. Nevertheless, the aft end of our boat constantly carries three major heavy items (in addition to the factory-stock targa bar and BBQ): our SeaCycle pedal-powered catamaran dinghy (about 180lbs), the liferaft (about 70lbs), and the backup Fortress anchor with chain (about 60lbs). As an aside, that weight back there has been comforting the few times we've gone screaming surfing down open-ocean waves. The boat's transoms have always been submerged which, from my old catamaran racing days, is a no-no from a hydrodynamic drag perspective. Thus, even before I bought the boat, in the back of my mind was always the concept of wishing it were just a few feet longer in order for the transoms to clear the water.
Over the years this concept gelled further ... in Florida, Tom Mestrits made some molds for his SW1000 creating a sugar-scoop and a few boats on the US East Coast were stretched. Here on the US West Coast, Stephan Wendl bought a set of those sugar-scoops and had his Seawind modified: when I sailed on his modified boat I was immediately struck by the very smooth silent water exit and noticeable pitch dampening when crossing the wakes of other boats. This further validated the concept, but I didn't have the time or inclination to perform the mod myself and I didn't want to entrust KatieKat to just anyone.
Anyway, spearheaded by Kurt Jerman (Seawind's US representative), the sugar-scoop molds migrated to the US West Coast and Joe Weathers with his Seawind 1000 Sea Ya undertook the mod to his boat, having had previous very nice experiences with fibreglass artisan Bob Dixon. On our way back from Mexico I followed his boat's modifications - we discussed the various options as he and Bob considered changes to the basic sugar-scoop. Joe's boat turned out very nicely (with the inboard side cut out) and so I decided to bite the bullet and have Bob modify KatieKat.
In the meantime, Seawind themselves undertook this change to the SW1000 and are now producing the very elegantly-executed SW1000XL with larger steps and other niceties.
To summarize, my reasons for wanting to extend the boat were to improve the aft end load-carrying capacity, have a clean exit of the hull from the water which should reduce drag and improve boatspeed, and the longer boat should provide not only improved boatspeed but a better-dampened motion in choppy conditions.
What follows are some of the issues I had considered as part of this hull extension exercise:
1. I've never been comfortable with sugar-scoops on multihulls, my reasoning being that if one is caught aback in ugly conditions (I mean, we're talking about really serious open-ocean storm stuff) and the boat gathers sternway then the transoms might dig in and hold the boat and perhaps allow it to trip over backwards. Admittedly a very remote and unlikely scenario, but those of you who have done this on a Hobie 16 will understand what I'm talking about. The half-open configuration whereby the inner aft side wall is cut down mitigates this concern somewhat and provides the added benefit of a comfortable dinghy boarding platform. For a while I had considered cutting down the outboard side wall as well, but in the end elected to leave it intact as it is certainly aesthetically more pleasing to have the full sidewall.
2. The converse to the above is, when running in a heavy seaway (I mean REALLY big stuff coming in from astern), that the increased aft buoyancy would push the aft end up and thus force the bow down. If I recall, some of the large ocean racing trimarans at one time had extremely fine tail ends for this very reason (I haven't followed their design evolution recently, so I don't know if that concept is still valid). Anyway, if it's that nasty I'll probably have all the sails down and be dragging a drogue and, again, I consider this an extremely remote scenario. I'd rather have the aft buoyancy.
I need to emphasize that the above two scenarios are pretty extreme and that in heavy-weather simply having a longer boat is, to me, indeed preferable.
3. The wide double outer-wall that the existing Seawind has (and the new SW1000XL) provides significant structural strength back there. Since the inboard side of the sugar-scoop is now cut out, the relatively thin outer (and remains of the inner) wall was doubled-up on Sea Ya. On KatieKat Bob used a much thicker composite wall section which not only provides superb stiffness and rigidity but has the side benefit of providing a perfect fit for the thick rubrail. Intuitively, I no longer have any structural concerns.
4. Breather holes were standard practice when we were building C-Class cats, allowing for the release of internal pressures created by solar heating and hull flexing. Joe had added a breather hole to his underfloor cavity (nicely brought out with a fitting and hose through the steering compartment) whereas I elected to not do that, my reasoning being that the total volume for thermal expansion is minimal and the wall thickness will preclude any hint of "oilcanning". If in the future I do an "oops" with my transom (or a speedboat shears it off) I'll hopefully still have the original boat intact.
5. Getting on and off the boat from the dock via the transom with the original SW1000 is to me a significant advantage over most monohulls (neener-neener). There are two elements to this: first is the ability to grab and hold the stainless aft rail which is so perfectly-placed up high and easy to reach. The second is simply the ability to step off the boat onto the dock off an aft step which is at the same height as the dock while still holding onto this grabrail. Our standard docking procedure (no external help, thank you!) is to approach the dock stern-first - Kathy simply daintily steps off one of the aft steps onto the dock, ties off the aft cleat to the dock with a very short scope, and then all I do is power the boat slowly forward and it cozies up comfortably to the dock. Absolutely no drama. I had two concerns with the transom extension: The first is that the outside hull extension (the coaming itself) would interfere with getting on/off the boat's aft steps directly off/onto the dock, but this fear was shown to be unfounded when I tried it on Joe's boat. The second concern is that the extended hull now means that Kathy doesn't have a convenient hand grip while she's standing on the aft platform. As I write this only a few days after retrieving the boat (been singlehanding), we haven't had a chance to see how this works out in practice.
6. On the subject of docking, my initial impression is that I think we will have to alter our docking procedure significantly because the aft cleat is now forward of the transom by a good five feet and the last thing I would now want is to tie off that cleat to the dock with a short scope and have a beam wind blow the bow off and exert a horrific load on this extended transom ... my preliminary thought is that I will simply back up to the dock, drop Kathy off, then turn around and nose in so she can grab a line off the bow cleat and then I'll simply back the boat to cozy up to the dock. We'll see, because I simply love docking the boat and demonstrating the absolute ease with which we can do it ourselves.
7. Getting on and off the boat from the inboard side onto a dinghy should now be easy, although I need to do it a few times to see if a more convenient grabrail shouldn't perhaps be added.
8. Getting on and off the boat from the outboard side onto a dinghy may now be slightly more difficult as one has to step over the coaming and the grab rail is quite far forward relative to the transom platform. Maybe simply grabbing the coaming may be sufficient. I had elected to NOT have any stainless work done as I simply want to think about it for a while after I see how things work out in practice.
9. Launching and retrieving our SeaCycle pedal-powered catamaran should now be even easier, as the inboard rubrails provide a nice rest and skid along which to drag the boat while it's being hauled up against the targa bar using the first reefing line off the end of the boom.
10. Pulling oneself out of the water onto the new platform. I've already demonstrated this as being significantly easier than with the old transom (I specifically avoid a boarding ladder back there as I do not want anything that might cause a twisted ankle - Seawind's SW1000XL solution with a cover over the ladder solves that problem). Good news, as I agonized over whether to cut out the coaming for a handhold or maybe add stainless rails: the new rubber edge protector provides a good handgrip and it's a simple matter of sliding oneself onto the aft step - the excellent non-skid that Bob used simply takes a little hair off one's chest! :-)
11. Retrieving a Man (or Woman) Overboard should now be easier as there is a larger platform onto which to haul the person out. Our technique (practiced, but never tried in anger) is to use the external Reef#1 line off the end of the boom to which I normally have a carabiner affixed (we almost never use Reef#1).
12. Slope of the aft step. I had wanted to ensure that water would not be trapped on the aft step and would shed immediately. I had discussed this with Bob and indeed the aft platform sheds water nicely with the boat presently trimmed level fore/aft statically. I hope that the rest of the boat's trim is unchanged, as that would affect cockpit draining in a rain and the shower drain in the head compartment.
13. Slapping noises when at anchor. With the transom now out of the water, small wavelets can slap against the hull and could prove disturbing to one's sleep. I had experienced this on other boats. Anyway, there's not much surface area there and it should only be audible to someone sleeping in the starboard aft cabin. We'll see.
14. Increased recurring costs. The world has changed and, whereas marinas previously charged by boatlength, they've now discovered that they make more money if they charge by their slip length; thus, I've often been charged for a 40' slip into which I put my 33' boat. We'll see...
So, those were some of the thoughts running through my head as I debated the hull extension configuration ...
Whew, finally found a place to dock KatieKat for a month and returned home. Had a lovely sail down to Long Beach from Marina del Rey, and I continue to be quite happy with the elongated boat's performance. Bob Dixon had taken a number of photos of the modification as it progressed, and I'm showing off a few of them here.
You can see the 3/4" core strips Bob had laid up to form the smooth hull shape. The aft underdeck is simply a hollow cavity.
The longer green stripes further add to the impression of sleekness.
This picture perhaps best shows off the minimal intrusiveness of the elongated outside hull surface when stepping on/off the dock.
Added 12 September 2007 These photos show how nicely the SeaCycle skids up/down the extended transom. In particular, hoisting the SeaCycle is now even easier than before.
I'm writing this just after completing the 400nm sail from Southern California to the San Francisco Bay Area - all of it into the wind and some of it in some fairly bumpy conditions. The following are a number of my initial random thoughts based on this somewhat limited experience.
First of all, I was surprised at the amount of water sloshing over the transom - most of it on the leeward hull. There are two distinct types of sloshes -
1. Water comes into the cutout from the inboard side and hits the outboard side of the boat from the inside. It flies onto the boarding platform at whatever the forward velocity of the boat is and sheds quickly. The platform is dry in smooth water, but as the seas get more confused the more the water sloshes onto it.
2. While beating to weather at a fairly low speed, as the boat pitches up on a wave the transom dunks and water flows onto the platform from astern, and then slowly flows off when the boat levels.
To my mind there's nothing particularly bad about this - one could even say that in the second instance the temporarily added weight of the water on the transom swimout might actually dampen the motion as the bow comes down.
When Joe Weathers and I compared notes on this, he even allowed that maybe raising the transom platform and having it be level with the first step (from the bottom) would eliminate a large percentage of this sloshing - this would add more reserve buoyancy, wouldn't affect getting on/off a dinghy or the dock, but would make it much more difficult to get back onto the boat from the water without a boarding ladder. This is an interesting concept that perhaps someone might like to pursue, but because I do not have a built-in boarding ladder on the transom I am happy with the mod the way it is (and the way the production SW1000XL is built).
First of all, let me emphasize that this consideration only applies when beating to weather. On virtually any other point of sail it is a non-issue and we've had some incredibly comfortable passages in heavy-sea reaching and running conditions in the original KatieKat.
First, some background on the existing design and our configuration: I need to emphasize that KatieKat simply NEVER hobbyhorsed. Let's make sure we understand the term: simply put, hobbyhorsing is a repetitive pitching motion or oscillation which results from having excessive weight at the ends of the boat. Now, on KatieKat we have never had a problem with this because I have always kept the bows extremely light - not only are the forward ends inside pretty much empty, but I even stow the anchor close to the mast. The motion we have is such that whenever the bow(s) hit a wave the boat rises quite sharply, but then when it comes back down it doesn't repeat the motion (which would be hobbyhorsing). Now, even though this is sudden sharp motion, the center of the boat (where the bunk, main saloon, and galley are located) experiences MINIMAL motion - a cup of coffee in those locations simply WILL NOT SPILL!
Now, the weight of all our cruising gear has to go somewhere. When passagemaking I bring out the heavy stuff and place it centrally in each of the hulls by the main bulkhead - heavy stuff meaning para-anchor and its three long heavy tethers and bridle and its retrieval line which are now made easily accessible in the starboard dinette area in an emergency, and, when crossing oceans, I also bring the anchors and chain down below and place them under the portside boudoire table alongside the two 20-litre spare water containers. Canned goods and books and tools are amidships. The aft end of the boat stays a little heavy: not only are the permanently-mounted liferaft and SeaCycle dinghy attached to the targa bar, but the drogue and its tether are attached and placed on the port targa seat ready to deploy. Yes, the aft end is a little heavy but that doesn't seem to matter.
Now, there are three benefits and one detriment to this configuration of very light bows, heavy stuff amidships, and a slightly weighted rear end:
Lightweight Bow Benefits -
1. No hobbyhorsing - the boat rises up on one wave and then immediately settles back down until the next one.
2. There is an absence of bridgedeck contact with waves - this is VERY important and I can't stress it enough: we simply do not have any of the bridgedeck pounding which I've experienced on other catamarans. I think it is simply because the empty front end of our boat rises immediately, allowing the wave to pass under the bridgedeck.
3. Forward deck is very dry - the conditions have to be pretty yukky for us to have any significant water there. In seven years of cruising I've never resorted to putting on any foul weather gear when going forward to reef/unreef the mainsail.
The single detriment is the sharp upward pitching motion in rough seas - after a while it does get tiring during long ocean passages in confused seas even though we humans are typically located in the center of the boat. As an aside, I once tried lying down in the starboard forward bunk in some pretty nasty confused seas: it was untenable!!, whereas in the same conditions our centrally-located main bunk or main saloon settees were very comfortable.
OK, so now, what has changed with the extended transom? The most noticeable difference in the boat is it's significantly smoother pitching motion. The upward movement, although still quite rapid, has been smooooothed out. The downward movement also seems duller and dampened. The overall effect is that the boat just seems significantly smoother when beating to weather - nice! Admittedly, this is my impression based on only a few hundred miles of beating in conditions which, I swear, were no longer the confused seas we had off Baja Mexico but the more regular (but still significant) seas off the central California coast. Sorry, but I am a poor judge of wave height and wave period and simply cannot quantify the conditions.
The boat motion on other points of sail simply doesn't matter as KatieKat has always been very comfortable - my impression is that the longer boat simply straddles more of the wavetrains and is thus smoother in confused seas.
She's definitely faster, but when I tried a wide-open throttle test I still only got up to the 7.8 knots I had achieved when the boat was brand new ... but, each engine now has over 2200 hours on it and we have a lot more stuff onboard - sorry, I should have run a wide-open throttle test just before I had the boat lengthened. When sailing, there is a definite increase in speed - noticeable in light airs where I would guess 10% (e.g., 3.3 knots vs. the previous 3.0 knots) and maybe 5% midrange (e.g., 7.3 knots vs. the previous 7.0 knots, although I swear we seem to be motoring a good 1/2-knot faster at the motor's 'sweet spot'), and I haven't had the opportunity to go an any screaming reaches so I simply don't know yet how she does at the top end (we've previously seen over 15 knots in ocean surfing conditions). The smoother boat motion also means an increase in the average speed in lumpy conditions. We've been fighting the N->S coastal current all the way up the coast and, with a few exceptions, I've seen a disparity between the boat's knotmeter and the the GPS and thus I need to verify the knotmeter's calibration in a known zero-current location before making any wild claims.
Remember, KatieKat has two outboard motors. Normally I turn on a motor (usually motor with only one engine) when boatspeed drops below my threshhold of pain for a passage - this varies enormously and may be as little as one knot when ocean crossing or 3.5 knots (or, gasp, even more!) when in a hurry going along a coast.
When going to windward and I would decide to turn on a motor, and if there was even a little wind, then I would motorsail instead of simply motoring. Before the transom modification, simply motoring straight into the wind/waves with bare poles not only did not give us the best VMG but (depending on conditions) also resulted in occasional propeller ventilation and associated runaway revving - not healthy for the engines. The very light bows on KatieKat simply prevent the bow from burying and thus keep the motors immersed most of the time - thus, I need to emphasize that propeller ventilation has rarely been a problem, anyway.
Motorsailing has four benefits:
1. The sail dramatically stabilizes the boat, especially in pitch. This further prevents the occasional lifting of the stern and ventilation of the outboard.
2. Even with one motor gently ticking over, it is dramatic how much the apparent wind angle can be reduced. For example, when sailing to windward for best VMG in, say, 15 knots of TRUE wind, I typically set the autopilot for 39 degrees APPARENT. Even though she'll sail as high as 33 degrees apparent, this 39 degree angle produces a higher VMG and also allows for excursions within the autopilot's deadband. After turning on the motor(s), I can reduce this angle to 25 degrees or even as low as 19 degrees apparent and still keep the sail drawing, with a very satisfying increase in VMG.
3. The motor keeps the boat moving through oncoming waves. The boat doesn't get slowed significantly by each whap and then have to recover.
4. The motor keeps the boatspeed up which allows the fin keels to work efficiently and provide the much-needed lift when going to windward.
Incidentally, here's a comment on motorsailing technique: when using one motor, it would be logical to run with the leeward motor because it is immersed a little better; however, what I've found is that running the windward motor is preferable because it helps counteract the slight weather helm that results when a wind gust hits the boat and thus eases the load on the autopilot.
Finally, for those of you with RayMarine autopilots, when sailing or motorsailing to windward to an apparent wind angle (not compass), I change the gain from the usual setting of "4" and up it to "6" or "7" - this results in larger immediate swings of the rudder and thus increased responsiveness of the boat to windshifts.
All right, with the extended transom, what has changed? The outboard motor location, which previously was about five feet forward of the transom, is now about eight feet forward (I'll need to measure this to provide more accurate numbers). As far as I can tell, in wave conditions that would previously cause an occasional propeller aeration I can now motor without that occasional runaway. This was dramatically demonstrated to us on our last leg of our passage going up from Santa Cruz at night in fog in bumpy seas in 15-20 knot winds and going straight up through the Windjammers Race fleet (not a pleasant experience). To improve our forward visibility I furled the jib and elected to simply motor straight up the coast (and straight into the wind). I then even lowered the main to keep it from flopping about. With these new extended transoms the boat motored very nicely with negligible aeration compared to what would have occurred with the old configuration - this was indeed a pleasant surprise! I used both motors since I wanted to have instantaneous response in case I needed to make an immediate collision avoidance maneuver. As always, I adjusted the boatspeed to keep us comfortable for that particular sea state. My conclusion is that the extended transoms improve the boat's rough-water motoring and motorsailing capability.
What more can I add? After a month and about 500 miles I'm happy to say that I'm glad I made the modification and extended KatieKat's transoms.
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