Cruiser Design Critique

[LTDboatdesign]

Hello Everyone,

I have been designing the boat that I will someday build, and this is what I have come up with. We plan to use this boat for offshore and coastal cruising. We wanted a boat that was comfortable for two and could accommodate occasional guests. I needs to be easy to handle and have a comfortable sea motion. We will be cruising without an engine, so light air performance is important. Perhaps the most important is ease of construction. This boat has a hard chine that fades out at the ends. The idea being that I can cold mold/plywood strip the ends and use sheet plywood in the middle. The interior is laid out with a dinette, a large v-berth forward and a large aft berth.

Have a look at the attached photos of the model.

The following is a list of specifications for the boat.
LOD 28.5'
LWL 26.16'
Draft 4' 5"
Displacement 10986
Prismatic Co. .557
Sail Area 483
D/WL 274
SA/D 15.654
SA/Wetted surface 1.79
Capsize Ratio 1.62
Comfort Ratio 33.23
Ballast/Displacement 33%
Mast height above deck 35'

I appreciate your thoughts!

[Tad]

With no engine you might want to look arranging a sweep over one side worked from the cockpit. Row standing up facing forward, the best looks like the oarlock on the starboard side and a folding cockpit seat on port(for max oar length inboard of the lock)

It looks like the keel is a bit far forward......

Divide the waterline into 10 equal stations, zero at the stem and 10 at the stern. On the profile the mast should be a bit forward of station 4 and the keel root should start about station 3 and the toe should be a bit aft of station 4. All keel aft of station 7 is extraneous until you get to the skeg...it's a good place to reduce wetted surface.

For cruising this part of the world (PNW) with no engine I would up the working sail area some, though you can substitute a big MPS/drifter type sail set flying from the bowsprit.

[michael pierzga]

Manovering a boat without power is a challenge. Great rubbing strakes in the topsides and no overhangs like that bow sprit. Make it reefable

Rudder and keel draft look the same, cut the bottom off the rudder to avoid normal grounding damage.

With such deep draft at beer oclock you will either need long stilts to strap onto your legs or a dingy to get ashore. Id suggest a removable ,optimist dingy shaped , cockpit.

Remember that without side decks your cabin house sides will ride on the dock as your boat heels over in a gale...make them the same strength as the hull.

As Tad states sailpower is king. pump up the volume on the mainsail. Full batten, max roach, no backstays, B and R type rig.

[LTDboatdesign]

Thanks for the quick feedback guys,

Tad, As for the sweep I agree completely my wife and I owned an Ericson 27 which i mounted an oarlock at the stern so we could scull from the cockpit, it worked great. As for the keel. I tried what you described and found that the the mast is slightly aft of station 4, the keel starts around early and the toe sits at about 3.5. As for the keel aft of station 7, I like the longer keel for its ease of steering and help heaving to. However, when I calculated the Lead of sail area over CLR/CLP, with the sails shown, i have almost a 22% lead. So i don't know, maybe 22% isn't as much as i think, I did use a cut out of the keel shape to determine CLR. I don't know how else to find it without more elaborate computing systems.

Michael, The rudder is a few inches shorter than the keel, but perhaps it could use a little more taken out. As for the sailpower I really don't want to go to full batten sails, i actually prefer strait leech sails. But I have been considering raising the mast a few feet, so that could help up the sail area.

Thanks guys.

[michael pierzga]

The windage of a tall rig works against you when maneuvering without an engine.

A club footed jib is great for maneuvering and is easier to handle than a main in tight quarters.

I dont know your region, but when anchoring or docking a boat without power I like to use a stern mounted and launched anchor. Its easier to control a boat by the stern and going bow on the shoreline or dock on protects your rudder. Make it impossible for an anchor rode to become wedged between rudder and skeg.


The front of your keel should be protected with a battering ram shoe.

Greek style climbing steps built into the stem aids bow on boarding

[philSweet]

She looks like she would have an easy motion, but like others have mentioned, I'd try to work a little bit more power into the hull. Midship chine an inch deeper and wider and the run flattening out a bit more. She would stiffen up quicker that way. Pretty boat. Forget the double spreader rig, you won't be able to take advantage of it with that hull. I'd go single spreader with fore and aft lowers and I might shift the stays'l head up a bit more. Mounting the boom on three feet of track is really handy on this sized boat. The first reef is up. The second reef is the head of the main down to about the level of the stays'l. You can sqeeze a bit more area in the main by running the boom very low in light air and lifting it with an anti trip reef when novices are aboard. Also agree that if you could end the keel and begin with a skeg you would probably come out ahead. Can you explain that ballast percentage? is it 33% of the fully loaded vessel, or the unloaded one.

[peter radclyffe]

is it like the griffiths yachting world 5 tonner

[LTDboatdesign]

Phil,

Thanks for the feedback. Initially i designed the boat with a single spreader rig, but to get shroud angles above 10 degrees I had to have the spreader right in the middle of the mast. It looked a little funny, but maybe i should have another look. I am worried that by having such large unsupported sections that i will have to have mast that is the same dimension from bottom to top. No problem if i'm using an Aluminum mast, but I have been planning to use wood, with a taper. I apologize, the drawing shows an aluminum looking parallel mast. As for the Ballast, it is 33% loaded to the DWL. I like the Boom track idea as well, clever way to get the boom out of the way.

[gonzo]

What is the reason for the small cut-out in the keel?

[LTDboatdesign]

the idea with the small cutout keel is just to reduce a little wetted surface, but still retain some of the seaworthy qualities of the fuller keel. Its just a compromise. Ted brewer used to design boats with this style of cutaway, I havn't really heard if they were successful, or if it worked better on paper than on the water, who knows.

[PAR]

Lose the "Brewer bite" and incorporate a real skeg, for better maneuverability, while still offering prop/rudder protection and decreasing wetted surface. You'll still track like a freight train, but you also can expect a crisp helm response when required.

A rig of those proportions will do much better with a lead of about 15%. The standing rig looks overly complex for a sail plan of this general layout. It's only 450 sq. ft. or so of area. Did you calculate the CE with the fore triangle area or the combined headsails?

The hull form selected will be initially tender, though it'll carry momentum in ghosting conditions, assuming you'll have sufficient area to move her. I'd increase her SA/D to over 16 to handle this.

[LTDboatdesign]

PAR, Thanks for the suggestions, I think you, and others, are probably right in converting to a true skeg configuration. My CE is calculated using the combined headsails.

[philSweet]

For a wood mast, I'd go with single spreader with jumpers, although I don't really like jumpers. I grew up with them though.

[Chuck Losness]

I'll offer some practical comments. I am not a yacht designer, boat builder or a navel architect. I am just a cruiser who's been out here doing it since January 2006.
First off you have too many berths. Your guests will be few and far between and of very short duration. Set up your interior to sleep 2, dine 4 and party 6. Your forward berth will not be usable at sea except in the mildest conditions and then probably only down wind. Get rid of the dinette and the quarter berth and have two settees with a table that folds up against the bulkhead. The settees will be your at sea berths. You'll find that the quarter berth will just be used for storage so you might as well design for that from the get go. Your galley should be set up so whoever is cooking doesn't have to stand in front of the stove. They should be able to stand off to one side. If they have to stand in front of the stove, you might as well put a target on their chest because it is only a question of how soon a pot full of hot stew, soup, chili or whatever will come flying off the stove.
Without an engine you will need a lot more sail area. I really mean a lot more sail area. The wind doesn't blow 24/7 in coastal cruising. It is dominated by diurnal land and seas breezes. You'll only be able to count on afternoon sea breezes that will start to build in the late morning, reach their peak in the late afternoon and die off in the evening with little or no wind at night. You can never have too much sail area on an engineless cruiser. Use your SA/WS ratio as a guide here. That will tell you if you have enough sail area to sail in light airs. If it was me I would look for a SA/WS ratio of around 2.25 or more. You can always reef but it is impossible to get a taller stick to give you more sail area. Get an aluminium mast and boom. Don't bother with wooden spars. The cost for decent spruce for a mast is out of the roof and an aluminium mast will better anyway. There is a good reason why virtually all boats have had aluminium masts for decades.
Follow the suggestions of the other posters and get rid of the full keel. Instead go for what I call a cruising keel with a separate skeg hung rudder off the transom. The keel should have the proper shape so you can sail to windward and be big enough to support your boat when hauled out. You'll have to ask the design guys how big to make it and what the section shape should be.
Make a hard dodger part of the design. You will hate life very quickly without a dodger.
I could keep on going but think that I will end with one last suggestion. First a question. Why do you want to build a boat? If it is to save money, forget it. You can buy and outfit an existing boat for a fraction of the cost to build a boat. I have several friends who have bought Cal 29's from $1,000 to $5,000 and spent no more than another $4,000 to $5,000 to get the boat ready for cruising. I know of another couple on an engineless Cal 25 that paid under a $1,000 for the boat and another $1,000 to outfit it for cruising. Some of the Cal 29's had outboards on the transom and one even had a small diesel in it. The boat with the diesel was purchased on Ebay for just over $4,000.
If I were in your shoes, I would buy a Cal 29 or something similar and go cruising now instead of taking years to build a boat. Just my two cents worth. Good luck with your dream.
Chuck

[PAR]

Calculate the sail area and the resulting CE with the area of the fore triangle, not the individual sails.

Chuck's suggestion of using the SA/WS as a guide is a good one, though I'd shoot for a slightly higher figure, like 2.4. It's fairly easy to remove area underway, but a pain in the butt if your sail plan doesn't have enough, as you're stuck with down wind options only.

Was your CLP estimate using just the keel profile or did it also have the underwater areas of the hull as well?

Naturally, you'll need professional assistance before you commit to cutting material, just based on your apparent and general understanding of design. This isn't meant as an insult, just an observation judged on your questions, choices and approach so far.