SEA HANDLING STABILITY - OUTBOARD -VS- INBOARD BOATS

[Tugforme]

It has been some time since I have logged into Tugnuts, but I am back to seek input and opinion on how the attributes of two different style boats in the 30' LOA range are likely to affect their performance under way. The two styles are 1) Inboard diesel and 2) Twin outboard gas.
Taking a Cutwater 28 as an example of an inboard diesel style boat, the major attributes as I understand them include a narrow bow section, a keel under the engine and in front of the prop and rudder, heavy diesel engine mounted low in hull with shallow shaft angle, but only with an 8 1/2' beam.
Taking the Cutwater 288 as an example of a twin outboard style boat, as I understand it, the C-288 appears to have a somewhat wider bow section than the C-28, it has little to no keel with a dead rise that I think is around 17, it has less weight down low in the hull, but it has a 10' beam and two large outboard engines mounted on the rear of the boat.

So, what I am curious about is whether the larger beam of the C-288 would make it more stable under way than the C-28 or weather the weight of the low mounted inboard engine and keel would make the Cutwater 28 more stable under way. Any input, opinions and/or experience would be appreciated.

Thanks,

Tugforme

 

[tranmkp]

when you make the bow fuller in a smaller boat its going to pound upwind. (think Whaler 28's) Narrower bow sections will just do that. But as always different strokes for different folks - Some people don't mind the pounding, or they have a suspension seat!!!

 

[Submariner]

It has been some time since I have logged into Tugnuts, but I am back to seek input and opinion on how the attributes of two different style boats in the 30' LOA range are likely to affect their performance under way. The two styles are 1) Inboard diesel and 2) Twin outboard gas.
Taking a Cutwater 28 as an example of an inboard diesel style boat, the major attributes as I understand them include a narrow bow section, a keel under the engine and in front of the prop and rudder, heavy diesel engine mounted low in hull with shallow shaft angle, but only with an 8 1/2' beam.
Taking the Cutwater 288 as an example of a twin outboard style boat, as I understand it, the C-288 appears to have a somewhat wider bow section than the C-28, it has little to no keel with a dead rise that I think is around 17, it has less weight down low in the hull, but it has a 10' beam and two large outboard engines mounted on the rear of the boat.

So, what I am curious about is whether the larger beam of the C-288 would make it more stable under way than the C-28 or weather the weight of the low mounted inboard engine and keel would make the Cutwater 28 more stable under way. Any input, opinions and/or experience would be appreciated.

Thanks,

Tugforme

I don't understand what you mean by "sea handling stability". They are all small boats and they rock n roll.

The planing hull is going to want to flatter seas to go fast. The inboard diesels are much slower and will therefore cut the waves better in the chop.
Neither planing hull or inboard diesel is fun in 4+ foot seas.

I have a R27 with an F300 outboard. My WOT speed is 32 knots. We comfortably cruise at 25 knots. If it gets choppy, we slow down to 11-12 knots so we don't get pounded.
In my opinion, a 10' beam vs 8.5' beam on a trailerable pocket yacht isn't going to make much difference in the rocking n rolling. But a 10' beam is definitely roomier inside the cabin.

I'd recommend you go out for a test ride in an R29 and compare that to a R27 or C288.

I'm a recreational boater also. I'd rather sit at the dock sipping a mojito waiting on better weather than being tossed around in it.

Midjudged weather and was punished for it (Johnstone Strait, BC).

 

[ProtoSanto]

I traded in a C28 for the C288 two seasons ago. The first thing I noticed just stepping off the dock on to the C 288 was how much more stable it is over the C 28. This is true at anchor as well. As for being under way, Last year Halibut fishing 30 miles west of Newport Oregon we had a shift in weather. weather buoy recorded 7.5 ft. wave height at 12 second with north wind gusts to 24 mph. Sporty my fishing buddy said. We landed a 48 Lbs. Halibut then came in a 25 mph. On the C 28 I felt unsafe and came in at much less conditions and at slower speeds.

Last year we did a Fluid Motion event to Desolation Sound. I just couldn't slow down the boat enough to stay in line with the Ranger Tugs. The Rangers would slow down to 18 to 20 as the sea state got rougher, I would speed up to 30 to 32mph. The hull allows the boat to cut thru the waves without any loss of control or stability. Keep in mind the C288 preforms best at 37 MPH and has a top speed of 54 MPH . When I did slow down to match the Rangers it was like being on a plow, harder to control and detrimental to my fuel supply.

 

[TristenT]

I'll throw my 2 cents in. I have a c28 with the Volvo d4 260, to start the c28 and c288 are completely different hulls. The c28 style hull is rather unique in good and bad ways, the narrow semi displacement excels at 6-7kt displacement cruising for fuel economy. you can also crank it up and cruise at 19-20kt and still maintain a reletively good MPG. Having the semi displacement hull rise up out of the water but sit deeper than a planing hull it mitigates the slamming and jarring affect that you get from planning hulls, but the trade off is they roll the higher up out of the water you get the c28 the more it wants to roll in a sea or even start picking a side to lean on, this can be a very un natural feeling but you get used to it. This is where auto trim tabs that are fast would come in handy zip wakes or sea keeper ride or similar I have spoke with both manufacturers but have yet to see some one put them on a c28 or similar vessel so I'm skeptical about how they would perform on a semi displacement hull. I cannot talk as much to the c288 as I have not been on one but wider is always nicer and that full planning hull is going to get up on top of the waves and rip until it can't or better you can't take it. Last year I managed to put the c28 in many different sea states all in one season of boating up here in south central AK some more than I would have liked to. I will say the boat handles running into or putting larger seas on the cheek pretty well, at times I was able to run through 6-8ft close interval seas and maintain about a 17kt cruise. Once seas increased to 10-12ft at incredibly close intervals sub 10 seconds is when the boat had to slow right down. The c28 takes small to medium seas on the stern very well but caution should be used with large seas on the stern or the quarter she likes to start running with the wave and then heal over. Really the vessels are quite different and id personally say it depends what your after for speed, cruising style and fuel economy oh hand a very large purcahase price difference.