25 Tug questions...answered!

Pat Anderson · Posted: Sun Sep 17, 2006 7:28 pm Post subject:

OK, I resemble that remark! Really - either the CD25 OR a C-Ranger 25 is our last boat until we cash in the house...

Dora~Jean · Posted: Sun Sep 17, 2006 8:45 pm Post subject:

I've been following all of these calculations on power vs weight, hull characteristics, etc, has been of particular interest for me over the years, I've had nearly all types including a very efficient, high performance (but weight conscious) 31 ft sailing trimaran (20+ knots sustained several times).

Thought I'd throw in one of my CD-25 powering characteristics I experimented with about a year ago (after fitting out with all the cruising gear for a couple of years). I weighed the boat and trailer fully loaded with full 100 gal of gas, 1/2 full water, raft, raft motor, ice chest, 2 anchors/chain/rode, etc, but no overnight gear on this particular trip, weighed 7,400 lbs. My 11,500 lb GWR, heavy-duty, 27 ft long, Pacific trailer was conservatively estimated by the factory to be 2,000 lbs with side bunks and spare tire/wheel. That would make the boat 5,400 lbs.

The day I tested out on the ocean was calm, lifted 1 engine, started from dead stop to full plane with other 80 hp Yamaha 4-stroke, at 5,000 rpm I was doing 18 knots. 3 people on board, me and two 17 yr old teenagers with overnight gear, figure 800 lbs extra for us and gear for a total boat weight of 6,200 lbs. I was testing to see how well I could get back on one engine. For a lengthy run I'd operate closer to 4,600-4,800 rpm to not overstress the engine, but it worked beautifully. I then understood how my twin 80's work so well even on nasty days with big seas.

Just another data point!

thataway · Posted: Sun Sep 17, 2006 11:21 pm Post subject:

Dora Jean,
Very interesting--and shows the advantage of the semi dory hull form. Many planing boats that size would not get up to 18 mph on 80 hp.

The Tom Cat will not get up with 150 hp single engine light boat.--it is about 8 to 9 knots without lugging the engine.

Old Jim · Posted: Fri Sep 22, 2006 1:50 am Post subject:

Sea Wolf · Posted: Fri Sep 22, 2006 2:02 am Post subject:

As a reminder, here is the Alweather 8 Meter and the website:

chug,chug,chug,chug,chug,chug,chug,chug,chug............................................

LINK SCROLL DOWN TO SEE DRAWINGS!

Joe

Les Lampman · Posted: Thu Sep 28, 2006 4:36 pm Post subject:

Jeez...where does the time all go? I meant to get back to this much sooner but... Sad

I've had extensive conversations about the CR25 in the last week or so and things are starting to turn the corner in a very postive way. I got some good numbers on the hull that went to the Seattle Boats Afloat show and there has been a marked improvement in weight reduction. That boat with four batteries aboard but otherwise dry was just about 5900 pounds. The top speed jumped up as a result of that (cruise speed is now about what top speed was), the new sound insulation is working and the boat has really come together. The data I have is from the sea trial Jeff conducted with the folks from Passagemaker.

So, from my perspective it's a "good news; bad news" sort of thing. The bad news is that the boat isn't going to hit the original target numbers with regard to horsepower requirements and speed but the good news is that it's much, much closer and for a lot of folks now it will serve their needs.

There are larger trim tabs on the boat now and Jeff reports to me that between the weight reduction and the larger tabs that the boat operates a lot flatter in the "in between" speeds which makes them much more usable.

If (and that's a big if for a lot of folks that may consider this boat) you're looking for a 15/16 knot cruiser with a full cruising load aboard (that means full fuel, water, dinghy, all your wordly goods, food, and the crew...maybe 7500 to 7900 pound total boat weight) the Yanmar 125 still isn't going to quite get there. With 40-odd gallons of fuel, some gear, and three folks aboard it's topping out in the 16 knot range but it's not able to cruise there although cruising at 13 now seems to be achievable and comfortable. It's still going to take some extra ponies in the engine compartment to get the heaviest CR25s cruising in the 15/16 knot range. For folks that are keeping a lighter boat and perhaps daytripping and weekending the boat would do pretty nicely the way it's operating now after its diet.

Now we'll just sit back and see how things develop with other engine choices. I'll be very happy to see our boats arrive here...I think it's really going to be a winner. Smile

dtol · Posted: Thu Sep 28, 2006 8:17 pm Post subject:

Les

It sounds a little like your saying that it needs bigger trim tabs in the down position to keep the bow down at mid-range speeds. Wouldn't it be less fuel effecient having to drag the trim tabs through the water all the time? Or is the adjustment in bow rise pretty minor? Jeff seemed to indicate that the lighter version runs pretty flat naturally.

wailedcentipede · Posted: Fri Sep 29, 2006 1:02 am Post subject:

a good plane is to get your butt out of the water (stern) ??? would the trim tabs down be less drag than running with out using them ??? not really a true comparison but when i cruise on plane at 3100 i than trim using the leg (inboard/out) and my rpm will jump a good 400 rpm, throttle back to 3100 the bows down butts out of the water your flying ... for sure different boats ... good performance on plane is to lift the stern up ... puts the bow down more boat surface touching the water but your skimming on top .... ok boot me .. lol .. cheers wc

dtol · Posted: Fri Sep 29, 2006 1:14 am Post subject:

Well, I think the issue here is at lower speeds in the semi planning mode when the bow wants to rise too much.

Les Lampman · Posted: Fri Sep 29, 2006 3:29 pm Post subject:

Sorry I don't have any specifics yet; I haven't had the chance to run the lighter boat. Jeff and I talked about it a lot and he did say the boat was running flatter. It also does have larger tabs. Whether or not these two directly correlate I'm not sure. I suspect that depending on boat loading it will take some amount of down tab to keep the bow where you want it at less than full planning speeds which is true of just about every boat we have here (including the C-Dory boats and Arima boats). The tabs should extend the comfortable operating range of the boat allowing you to drop to speeds that the hull otherwise wouldn't be happy with.

Les Lampman · Posted: Fri Sep 29, 2006 3:35 pm Post subject:

dtol · Posted: Fri Sep 29, 2006 7:25 pm Post subject:

Has anyone had this boat out where they could experience the roll characteristics? Does the hull have hard chines which are effective in dampening the roll from wakes and bigger seas?