stuck in the hole, getting up on plane

J

jimmyg

New member
Hi;

I have narrowed my prospective choices of purchase down to a few boats. I will operate these and perhaps a few more before I buy. After reading and lurking , I believe that I know just enough to be dangerous--


Performance-

Tomcat-- rises up upon acceleration (parallel to the water , does not get stuck in a hole (read- angled bow upwards), and will sit down flat upon deleleration rather than digging a hole.


Rosborough -- ditto above except a slight angle up and a slight hole down- I could call Les and ask him , but then he will just explain it all to me and I will feel guilty about bothering hime cause he has already offered me a ride and I plan on taking him up on it during the holiday season


C-Dory 25, 26 , Seasport Aleutian 26 (outboards), Osprey 26, Skagit 27--
digs a big hole upon acceleration and falls into one upon deceleration

All 3 plane thru 1-2 foot chop, dont like 3 foot chop and must be operated at slower speeds than their respective planing speeds and the Rosborough probably is happier in the stuff.

Did I get this right, I'd just love to have your comments .

Again thanks for all the previous help
Jimmy
 
Hi Jimmy,
A few points from my perspective. The Tomcat will just eat up chop up to three feet with comfort on plane. In fact, the Tomcat offers the most comfortable ride when on plane. In conditions that you would expect a slam the Tomcat floats right over. This is what ultimately sold me on the Cat.

Any vessel coming off plane will fall into a bit of a hole. Only if you're loaded stern heavy would it really be an issue. Similarly when accelerating, if you're stern heavy you will plow a deeper hole and ride with a higher bow. The Tomcat does stay quite parallel compared to monohulls I have cruised.
 
The C-Dory 25 and 26 should have less squat and bow rise than deep V boats like the Sea Sport and Orca. Because of the flat bottom the C-Dories have a very low planing speed and transition very seamlessly.

The flat bottom also means a rougher ride, especially in head seas. In following seas the C-Dory handles great.
 
I hate to add another boat to your list but it would be worth looking at Campion's Explorer model at the boat show, if a 22' model is suitable. It's a deeper V than C-Dory and has a flexible layout instead of a permanent dinette.

Most important, it's made in Canada, and with the favorable exchange rate, it could be a bargain.

If 25' fits your needs, I definitely go with the Tom Cat, given it's ride and room.

-Greg
 
None of those boats will have an objectionable amount of bow rise or fall if run properly. Even if you tried to get the nose in the air, I don't think it would be objectionable.

My concern is that you are kinda all over the board on hull shapes. In car terms I might describe it as looking at Corvettes and Chevy Suburbans- each does what it's intended to do very differently.

My understanding is that the Venture 26 gives a better ride in a chop than the C-Dory 25. Neither of them should "dig a big hole"- their draft isn't enough to dig a hole.

But what is important to you- the ability to pound away offshore in 4-6' seas, or fuel economy? Afraid you can't have both. Keep in mind also that any boat this size will not have the offshore abilities of a 50 footer, or even a 30 footer.

The factory recomends the C-Dory 26 Venture have 175 horses on the transom. What does the 26 Osprey need- 250 or more?

So do you get a boat for the 10% of the time that you may encounter big water, or do you buy a boat for the other 90%? Most boaters are fair weather boaters, avoiding big seas. And the C-Dorys will handle "big" seas, it's just they'll handle it differently.
 
If money to purchase a boat or towing vehicle required is not an issue, buy the Tomcat and be done with it. It has the largest cabin/cockpit area and the smoothest ride.
 
Lots of great answers above. It is not at all simple--there are many different hull types. It is way beyond the scope of this forum to discuss all types of hull form--that is something that JimmyG needs to do on his own. I sound like a broken record--but at least do some reading--the best book is "the nature of boats" by David Gerr. But there are internet articles about the different hull forms.

From the Hull design forum: "Displacement hulls are designed to travel in the water at a typical hull speed of 1.34 *(square-root LWL) in knots. This formula applies to the distance between bow and stern wave crests. At faster speeds, wave making resistance increases exponentially because the vessel is trying to climb on top of the bow wave - meanwhile the stern is being sucked down by the dynamic forces from the "hole" created in the water as the vessel moves forward. Displacement hulls tend to have pointed bows and sterns because this form poses the least wave making resistance at "displacement" speeds. It takes a relatively small amount of power to push a displacement hull at its "hull speed."

Semi-displacement hulls tend to have wide, flat aft sections - like a New England lobster boat. These hulls are designed to partially climb on top of the bow wave and separate the transom from the stern wave. Semi-displacement speeds are usually in the area of 1.5 to 2.5 *(square-root LWL) in knots. It takes a *lot* of power to drive a hull in the semi-displacement speed range. The flat wide stern sections help to provide additional lift in the stern to partially overcome this problem.

Planing hulls are designed with straight sections aft. A typical deep-V bottom hull has the same angle to the 'V' (the same "deadrise" angle) from midship to transom. They are designed to climb completely out of the water at high speed and "hydroplane" on top of the water. At planing speeds, water is breaking cleanly from the transom and the hull is riding on its straight aft sections. The greatest resistance at planing speeds is frictional resistance. It takes more power to climb out of the water over the bow wave than it does to maintain planing speed once this is achieved. At very high planing speeds (>25kts) any change in deadrise angle in the aft sections of the hull can adversely affect performance. Hulls with a "variable deadrise" angle in the aft sections (where the angle of the 'V' decreases and flattens toward the transom) are a further modification of the semi-displacement hull form. They are more easily driven at speeds < 25kts, but at higher speeds tend to push the bow down due to the higher dynamic lift in the aft sections. Variable deadrise hulls can actually become unsafe at very high speeds >30kts because of this tendency - it is possible for the bow to dig in and cause the boat to broach at high speed."

The Tom Cat is a planing catamaran (Most cats are semi displacement hulls), and is faster than most cats with the same HP (also more economical at higher speeds, but not some lower speeds), but is more likely to slam as you get into higher seas. A 3 foot wave is considerable--and the Tom Cat will handle a 3 foot wave better than any of the other boats you have mentioned. Something like a Glacier bay will do even better, at least going into the waves--but not as well going beam to the seas or down wave. Realistically how often will you be boating in more than 3 foot seas?

The Rosborough is a semidisplacement hull (like a lobster boat--rounded chines, small keel, fairly flat run aft, and deep forefoot). It is going to take more power to push at the same speed as the C Dory--and will not come on a plane at a lower speed, but can be pushed to a plane with enough HP. If you want to run at 8 to 15 knots in moderate seas--this may be your best choice--if the layout and other features of the boat are satisfactory.

The C Dory will plane at a very low speed--it is a semi dory--very seaworthy--but can pound if driven into a steep sea. The way around this is to put the bow down with trim tabs and permitrims--this presents the V of the bow to the seas--it will throw some water, but you are in a pilot house boat--so no problem. On the other hand--the C Dory will ride better down waves than the semidisplacement boat. The C Dory and other boats you name are quite different--and behave differently. The C Dory probably has one of the slowest planing speeds of any boat built,, because of the hard chine (reverse chine)--flat run, with a little rocker and the use of tabs and Permatrims.

JimmyC--you cannot read some forums and then go out and buy a boat. That is a major mistake. You need to ride in every boat you are considering--and some others in all different conditions. Some folks push a certain boat, because they own one--or because they are convinced it is the best boat...for them. There is no "perfect" boat.

You don't want to rush into buying a boat. Take your time, do lots of sea trials and enjoy the process--much less likely to make a mistake.
 
Bob made a lot of good points. If you are interested in riding in a lot of different boats give Master Marine a call. I went to a demo day that they did last year before we bought the C-Dory and they had a TomCat, C-Dory 22, Osprey 28, and a Skagit Orca in the water at Cap Sante.
 
thataway":3sikpk1d said:
... A 3 foot wave is considerable--and the Tom Cat will handle a 3 foot wave better than any of the other boats you have mentioned. Something like a Glacier bay will do even better, at least going into the waves--but not as well going beam to the seas or down wave. Realistically how often will you be boating in more than 3 foot seas?

...
Click to expand...

An important point to remember is that Bob is referring to a 3' chop type of wave, not to be confused with swells. If you are discussing sea capabilities with others for example, this could be a significant misunderstanding.

You can have measured 10' swells and comfortably cruise over them in a dinghy if they are spaced far enough apart (i.e. longer period). If the winds are stronger causing cresting or if the swells are close together, it changes the game of course. The Tomcat can handle true 3' waves on plane.
 
Thanks, Matt

Yes, the wave height vs the peroid of the wave is extremely important. A 3 foot wave at 4 seconds interval would be very steep and hard on most boats. A 3 foot wave at 20 second interval--would be a smooth up and down motion--not perticularly noticable.

You can make a "go/no go" chart based on this prediction--lets say that 3 feet at 6 seconds is your tolerance. Then 4 feet at 10 seconds may also be within your tolerance. Some boats 2 feet at 5 seconds may be too steep for comfort.
 
Jimmy,

All good advice. Just want to add that different knds of boat require that you learn their different handling characteristics and deal with them.

I cannot drive our RF246 the same way as I drove our CD22 or our 25 Grady or any other boat that we have owned and all of them are quite capable of surviving sea conditions that we do not care to be in. Have also been in a TC255 in sloppy conditions and agree totally with the above, it is really impressive as long as you can stay on plane.

If you go for a ride with Les it will be in an RF with twin Honda 150's and I am sure that he will do a "water ski" take off for you and he won't need the trim tabs. You will need to hold on to something.
We have twin 135's which is more than adequate. Twin 90's are quite sufficient.

They are all good boats, as yet I don't think anyone has managed to come up with the perfect compromise that fits all sea conditions and all user desires. If you want a good fast ride under ALL sea conditions then you would need either a very big boat or a submarine.

The MegaMillions lottery looks good this week.......

Merv
 
Ah, the angst involved in picking out a boat. Dr. Bob has distilled the major differences in hull types to an easily understandable form. Others have added pertinent considerations. Test rides on the various boats may give you an idea of how the boat rides in that particular condition... but in actual usage, the conditions will vary every day. There are people using each of these boats right there in your area, so you have a good idea that any of those choices can work. With that in mind, consider how you will use the boat. Really. After the newness has worn off and you've taken all the neighbors and family for a ride - how do you see your day to day use of the boat?

Is it comfortable? Enough seating for the people you'll normally have along? Enough creature comforts? Are you going to be overnighting? Then you'll want to be sure you fit the berth space. How about the potty situation?

Now, about that hole-shot... we have found that who gets on plane the fastest isn't the most important use of the boat (we don't water-ski :wink: ). I generally use a slow, smooth throttle motion to get on plane; then trim the boat, adjust the throttle, and use the fuel flow meter to find the most efficient speed for that particular trip. Some days we just like to putt along, other times we want to make some miles.

So, the dilemna: any of these boats will handle most of the conditions most of the time where you boat. A couple key words there: any and most. There will be conditions where you don't want to be out in ANY of these boats. As your experience expands, you will find your comfort limits. As long as your budget allows, you can pick based on what you consider optimum speed, ease of handling, ride comfort, and how the boat appeals to you. I think if pressed, most of us will admit an emotional attachment to our boats... so put how the boat looks to you into your decision making process, as well. If, as you walk away from the boat, you find the desire to turn and look at it one more time and say to yourself, "Damn, that's a good-looking boat!" then you've found your choice.

You can make any of the boats on your short list work... not a bad decision making situation to be in. :D Good luck with your decisions.

Best wishes,
Jim B.
 
Nearly forgot. One thing to make sure of before you even think of doing a full power "hole shot" (on any boat).

Make sure your trim tabs are set the same on both sides otherwise it gets very amusing.. fast. BTDT.
:oops:

Merv
 
jimmyg-

Lots of good advice above!

If you're like a lot of us.............

Your biggest friends are patience and time.

Use them to research, try out, and digest all the information and experiences before you act (buy).

Go to a C-Brat Get Together and see those boats available and all the other brand dealers and get as many looks, rides, and opinions as possible. Then digest it all!

There have been and will be some great bargains coming along because of the economic times.

Your biggest enemies are impatience, too much enthusiasm, and impulsiveness.

Too many people get all wound up and buy the wrong boat the first time!

You situation on Lopez Island may be pushing you forward, but take your time if you can.

With the bargains available, be ready with cash or financing to jump on the boat you want once you're sure of the choice. The best ones don't last long.

Buying new is another choice, with some bargains available because of the recession, and also because some dealers have last year's overstock of left over 2007 and 2008 models.

And don't just do it rationally, use your intuition and wait, if you can, until everything about the boat and your anticipated using really "feels just right"!

The more time you give it, the more likely you'll be satisfied with your final choice!

Good Luck!

Joe. :teeth :thup
 
thataway":2114wpfy said:
Thanks, Matt

Yes, the wave height vs the peroid of the wave is extremely important. A 3 foot wave at 4 seconds interval would be very steep and hard on most boats. A 3 foot wave at 20 second interval--would be a smooth up and down motion--not perticularly noticable.

You can make a "go/no go" chart based on this prediction--lets say that 3 feet at 6 seconds is your tolerance. Then 4 feet at 10 seconds may also be within your tolerance. Some boats 2 feet at 5 seconds may be too steep for comfort.
Click to expand...

Marine weather forecasts for oceans include predictions of wave periods. I have yet to see a forecast of wave periods for the Chesapeake Bay. Marine forecasts for the bay give wave heights without periods. Does anyone know why are periods not part of the forecasts?

Roy

_______________________________________________________________________
"Life is complicated. Ideas are simpler. That is why they are attractive."
 
Roy, we spend a lot of time on the Bay and, this is just a guess on my part, but I think it has a lot to do with the confined spaces. There's just not a long enough "fetch" for the waves to build up any pattern like there is in the open ocean or a bigger body of water.

It's really only when the wind is either North or South, when you get it acting on the water for a very long distance that a regular period occurs in the Bay, and then not for a long period of time until something changes.

Just a guess but based on 32 years in the Navy, I think a fairly "educated" one...

Charlie
 
YACD":5k9fy98e said:
thataway":5k9fy98e said:
Thanks, Matt

Yes, the wave height vs the peroid of the wave is extremely important. A 3 foot wave at 4 seconds interval would be very steep and hard on most boats. A 3 foot wave at 20 second interval--would be a smooth up and down motion--not perticularly noticable.

You can make a "go/no go" chart based on this prediction--lets say that 3 feet at 6 seconds is your tolerance. Then 4 feet at 10 seconds may also be within your tolerance. Some boats 2 feet at 5 seconds may be too steep for comfort.
Click to expand...

Marine weather forecasts for oceans include predictions of wave periods. I have yet to see a forecast of wave periods for the Chesapeake Bay. Marine forecasts for the bay give wave heights without periods. Does anyone know why are periods not part of the forecasts?

Roy

_______________________________________________________________________
"Life is complicated. Ideas are simpler. That is why they are attractive."
Click to expand...

The best resource I have found for wave period information is here:

http://www.ndbc.noaa.gov/maps/Chesapeake_Bay.shtml

Good question as to why they are not included in marine forecasts, perhaps too difficult to predict?
 
I see lots of info there Matt from the stations and buoys but nothing about Wave Period, which was the question. Am I missing something you see about it?

Charlie
 
Captains Cat":2i9acv2e said:
I see lots of info there Matt from the stations and buoys but nothing about Wave Period, which was the question. Am I missing something you see about it?

Charlie
Click to expand...

Hi Charlie,
You select a water based buoy (such as station 44009 - highlighted in blue) and it's listed 2nd line from the top (once you scroll down to the data section) titled "Dominant Wave Period".

Checking again I see that is the only in-water buoy for that area. The green and red markers are land based and do not provide wave period data.
 
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