I've been waiting a long time to post on the Brats here about the C-Ranger 25. I've spent a fair amount of time around the boats and have had the opportunity to run one in Puget Sound. I do have a lot of experience with boats of this type and I have a farily extensive knowledge of yacht design having intended to go into that field many years ago. The following comments are based on computations using known and accepted formula in the yacht design profession so if you have an argument with my assessment make it on the basis of how the math works using accepted criteria.
There are lots of pieces of the puzzle but two of the main items are weight and waterline length. Neither of these figures are published so I'll have to use what I've learned of the boat for weight and take an educated guess on the waterline length. Also note that all the formulae used in yacht design are computed in knots; mph are for ski boats, bass boats, and cars...true cruisers operate in knots (after all that's what the 'miles' are on charts).
From the waterline length we can derive the square root of that number which a key ingredient in many computations. We'll use 24-feet since the overall length is listed as 24'7" and the tansom does angle back just a little. The square root of 24 is 4.9 (rounded off). For the sake of making this easy we'll just round up to 5.
The hull speed of a boat is generally considered to be 1.34 times the square root of the waterline length (5 in our case) which is called the speed-length ratio. In this case 1.34 times 5 gives our hull a speed of 6.7 knots. Beyond this speed we start to venture into semi-displacement speeds which is generally considered to be from hull speed (S/L of 1.34) to about a speed-length ratio of 2.5 to 3 (the former for light flatter boat the latter for heavy deep-v hulls). Beyond a S/L (speed-length ratio) of 3 the boat is definitely on a full plane. For the C-Ranger 25 that means semi-planning speeds start at 6.7 knots and extend to about 13.5 knots (2.7 S/L); at an S/L of 3, which is 15 knots, the boat should be on a full natural plane.
For this type of hull it requires about one horsepower for every 80 pounds of boat weight to achieve approximately 15 knots. Taking into account the empty weight of the boat, electronics and accessory add-ons, full fuel, full water, safety gear, personal gear, a dinghy, cruising supplies and a couple of folks we're likely in the 9,000 pound range. That means to move the boat at 15 knots we need 112 horsepower (9,000 pounds divided by 80 pounds-per-horsepower). This is in CALM water; powering into a headwind or seas will require more (sometimes much more) horsepower. The Yanmar 125 can put out a continuous 116hp at 3700 rpm; you can see with any appreciable wind or sea state crusing at 15 knots is not going to be achievable quite often and only at the max the engine can put out which is not something most of us want to do. The fuel burn at 3700 rpm is a bit over 6 gallons-per-hour which yields in CALM conditons about 2.35 nautical miles-per-gallon.
A note on weight...the information I recieved on the first CR25 was that it weighed 8500 pounds with fluids (not including the trailer). The first hulls are usually heavier because so much work is done by hand and the production hulls should be a bit lighter. Subtracting fuel and water weight and the equipment hull #1 had (anchor and rode, Raymarine E-120 with radar, etc) the empty weight of the boat was about 7500 pounds. Assuming they can trim that back to say 7,000 pounds we'll add about 1,000 pounds for liquids, electronics, safety gear, dinghy, and such bringing us to 8,000 pounds. We then need to add the weight of personal gear, galley gear, food, and folks (and accessories like a microwave, generator, etc). I suspect in the water with the crew aboard this will put most CR25's in the 9,000 pound range. Remember for every 80 pounds you put aboard the boat it requires one more horsepower to push the boat at 15 knots.
For comparison, 19 knots (about 22 mph) would require that the horsepower-to-weight ratio be down to 65 pounds-per-horspower. To achieve this on the C-Ranger 25 with the Yanmar 125 means the fully loaded boat (with the crew aboard) could weigh no more than 8,100 pounds; that's a tough number to hit on a CR25 loaded for cruising although it's possbile for a very light new boat. At 9,000 pounds it would require 140 horspower to achieve the same 19-knot speed.
The two most important items that are overlooked with regard to performance are weight (especially on planning hulls) and sea state. The higher speed you wish to attain the lower the weight has to be per horsepower (all the way down to about 28 pounds-per-horsepower at 30 knots). Wind and rough conditions require a lot more horsepower than folks normally allow for.
Speeds for boats like this are very difficult to report accurately without totally controlled circumstances. Any change in sea conditions, wind, weight, trim or current will skew the results and small changes yield big percentage changes at the speeds we're discussing here. For instance, it isn't unusual at all to have 2 or 3 knots of current here in Puget Sound. If the boat is acutally running at 12 knots through the water then the reported speed running with the current will be (with a 2 knot current) 14 knots; the opposite direction will only yield 10 knots. That's a 4 knot difference...about a 33% percent difference in reported speed at 12 knots. If you then add wind (even 8 to 10 knots makes a big difference) things get skewed even more.
There is no indication that this is anything other that a full planning hull and the design has not been optimized for semi-planning speeds; which means, like most boats, it's not particularly happy "in between". Since it carries a moderate "V" at the stern it does not drop the stern as much at slower than planning speeds as a deep-v hull does but it's still not the best running attitude. I found the boat delightful at 7.5 knots (burning 1.3 gph) with the bow slightly up and a bit of lift in the stern stabilizing the boat. At 8 knots the bow was rising too high for good visibility and was starting to climb the bow wave (as all boats will). I wasn't happy with the running attitude again until approximately 12.5 knots when the bow started to drop on it's own; prior to that it took a lot of trim tab to level things out. In a two-way run done twice I was able to achieve 13 knots (or just a shade over) at wide open throttle with the Yanmar 125 installed in the boat I was testing. I wasn't able to achieve full rated rpm as the prop wasn't correct and they were still dialing that in with additional testing planned.
I'm very happy with the boat's physical properties; they've done a superb job with space utilization and there a real "sense of space" inside the cabin. Real people can move around and access things easily. The hull runs as I expected it to; it tracks much better than most at modest speeds (my favorite 7.5 knot speed) and it appears when given sufficient power it will run nicely in the upper teens at a fast cruise though I've yet to test it there. My sense was at 13 knots we were just getting to the point where the hull was starting to flatten out on its own; I think another couple of knots would have done the trick. Most of us won't want to run the 125 as hard as it's necessary to do to obtain a 15-knot cruise and extra weight, wind or sea state will leave you shy of that mark with the engine spinning at 3700 rpm at its max continuous horsepower.
dtaol wrote: (My comments are below his marked >>)
Here are some additional questions.
1. How about the noise level outside and inside of the cabin at different speeds?
>> The first boat was reasonable but not quiet and more and better insulation has been added.
2. Smell. Does the exaust follow the boat around at slow speeds?
>> This wasn't noticeable on my seatrial; the engine exhausts on the side and not under the swim step and I suspect this helps.
3. Will the deisel engine operate at trolling speeds of less than 2mph and at length?
>> There is too much thrust from the prop and I believe the lowest speed will be about 3 knots though that's a very hard number to measure for in moving water.
4. Can you mount a kicker on the back some place? What kind of modifications to the hull would it take?
>> None to the hull; there's a very robust full-width swim step mounted on the transom. It will probably require a mount attached to the swim step.
5. Would the two floor storage compartments work as fish boxes, and could they be insulated and fitted with macerator pumps ala TC-255?
>> Both of the hatches in the hulls I've viewed gave access to things like batteries, water heater, etc; you wouldn't want to make these areas inaccessible.
6. Where could a dingy or raft be carried?
>> The only logical place if not deflated and rolled up is on the swim platform.
7. The standard features list indicates that there is a 6 gal hot water tank, but, doesn't say anything about a hot water heater. Is that included?
>> One and the same.
8. Does the $110K base cost include a trailer?
>> No.
9. How easily does it trailer and pull for long distances?
>> I don't have any direct experience with this yet but the CR25 doesn't require a special trailer. With the weight forward of the transom over the trailer axles it should tow quite well. I've a lot of experience towing boats like the Orca 24, SeaSports, Grady-Whites and such; this boat shouldn't be much different. It will launch and retrieve a lot easier than the typical deep-v hull. All up trailering weight should be in the 10,000 pound range (assuming full liquids).
10. Can the mast be used or modified to be used with a windlass to pull pots and launch and retrieve the dink?
>> No. Although a full custom mast could be designed as the mast offered with the CR25 is optional. The dinghy needs to go on the stern; there isn't room on the cabin top and using a davit lift on a small rolling boat to lift a dinghy is precarious at best.
11. Is the anchor roller a good one which would self deploy the anchor or will it have to be upgraded.
>> It's a good one. The windlass is set up nicely on the CR25.
12. Where is the Anchor locker? I haven't been able to pick it out of the available photos. Is it big enough to make retrieving the anchor a one person operation and not make mess out of the "state room"?
It's right at the bow next to the windlass; no mess in the forward berth area.
13. Does the Raymarine Navigation package include radar?
>> It's an option and so far they've indicated that the dealers will install the dome.
14. Is the cockpit canvas and side windows fairly priced at $2500 and as good in terms of quality and eficiency as other custom work you have seen on other boats?
>> I would consider the price to be fair here at our location given that I can have full custom canvas done at that price with high quality fittings and a great fit. I haven't seen the canvas offered through the factory.
