Deep vee hull

[Sneds]

I am led to belive that a deep vee planning hull will handle rough conditions better than a shq :confusedllow vee, makes sense to me.
But at what angle deadise would a meduim V become a deep V? /forums/images/graemlins/confused.gif

 

[Whitelighter]

I think DeepV's are above 20 degrees.

 

[gjgm]

all planing leisure hulls are some sort of compromise, I guess, between handling,accomodation and power required, and usually change shape/flatten towards the stern. The sharper the V at the bow, the better it will cut through waves. If you imagine the boat dropping into the water, you can picture that the flatter the hull, the more of a crash its going to make!
24 degress is certainly as much as I ve seen on a leisure boat, usually fast USA sports, though most seem a few degrees shallower.

 

[Whitelighter]

Our 23/24 foot boat has a 24 degree hull, which is reckoned to be pretty deep. I am not aware of a leisure bot of that size with a deeper V either

 

[KCook]

Most bowriders from US builders that are 20' or bigger will have at least 20 deg of deadrise. It's really only in the models under 20' that deadrise becomes an issue. The boats meant for minimum power (3L motor) may have as little as 16 deg. 18 deg is very common in these smaller boats. A fair number will have 20 deg. So, at least for small bowriders, the low-med-high scale would be 16-18-20.

And that is talking ONLY about fiberglass bowriders. Other types of boats will have different figures, and different standards. Tournament fishing boats (Donzi etc) run 24 deg. Aluminum runabouts and ski boats (Mastercraft etc) run less deadrise than fiberglass bowriders. So it's largely relative.

Kelly Cook

 

[Whitelighter]

I am sure you are right with the Donzi's etc (but they ARE performance boats mind.

Just to take a selection of a few US boats.

The 28ft Maxum 2700 here : 16 degree deadrise

The 35ft Bayliner 325 here : 18 degree deadrise

The 24ft SeaRay 240 Sundancer here : 18 degree deadrise

The 25ft FourWinns 258 Vista here : 17 degree deadrise

The 27ft Chapparral 270 Signature here : 18 degree deadrise

The 26ft Larson Cabrio 260 here : 20 degree deadrise

There is nothing wrong with these degree V's, but I think to claim that most US boats have a deep V hull over 20 degrees is, frankly, wrong.

I know Donzi do, but they are a bit specialist and are certainly not in the list of mass US manufacturers. In fact, one of the few mass produced US boats to have a deeper V is the Bayliner 285 at 21 degrees - always have liked the sea keeping of that boat.

 

[stelican]

Thats why it leans over so dramatically not good for swmbo

 

[Whitelighter]

excuse me?

 

[stelican]

Look at the photos you posted recently

 

[Whitelighter]

Oh, right. I get you.

Well, I think any boat you put into a turn at 40+knts is going to lean. Difference between a deep hull and a medium V hull is that the deeper hull will actually turn at that speed rather than loose grip.

Not advisable to do it every day of the week mind. And probably not with SWMBO on board.

Speaking of SWMBO, in choppy conditions she would be much happier with a deeper V - a lot less crashing, banging a slamming...

 

[KCook]

"There is nothing wrong with these degree V's, but I think to claim that most US boats have a deep V hull over 20 degrees is, frankly, wrong."

I did not say most US boats. What I said was most US BOWRIDERS. The cruisers that you cited are a whole different class of boat. Which is why I tried (obviously failed) to make the point that this "what is deep" question depends on the type of boat.

Kelly

 

[Whitelighter]

ah, ok. While I take your point that you meant bowriders, they are still paning hulls. Mastercraft etc have a near flat ull at the back becasue they are designed as ski/tow boats, for use on benign lakes where minmal wash and drag id preferable.

Stick one in a heavy sea at it would be aweful. Bowriders and cruisers are all planing hulls, and in that sense a deep V is a deep V regardless of the top sides.

21 degrees and above is deep, 16-20 is medium. Chris Craft are an example of a fine US builder, who have always produced Deep V hulls above 21 degrees

 

[KCook]

Excellent summary jezbanks. The one nit I would pick is that the Mastercraft is also a planing hull. They will easily exceed 45 mph. Which is well into the planing zone. But you're perfectly right about their low speed manners, outstanding at those speeds as well.

Kelly

 

[Whitelighter]

Yes, i understand that mastercraft use a planing hull, but my point was the very shallow v was for a very specific purpose i.e sking. /forums/images/graemlins/smile.gif

 

[Sneds]

Thanks for all your input.

The reason I asked is we are looking for a new boat, SWMBO likes the beamier models from the US, white shiney & pointy.
Our location is the Bristol Channel, which can get a bit lumpy at times!
So am I right that with 25'-28' sports cruiser, we should be looking for a medium deep V as per the examples above? 16-20 degrees, the higher the number the better ride?

PS just for info, we have on our short list, a Cranchi Perla 25 (never heard of these buts looks nice), a Larson 254 cabrio, Searay 260, but my fave- Sealine 260/270 OR 290.

Cheers /forums/images/graemlins/smirk.gif

 

[Nautorius]

I am sure our Chaparral 240 Sig had a deadrise of 23 degrees and it was awesome in the rough stuff.

Deep V is the way to go...hence why I have a Scandi Boat!

Cheers

Paul /forums/images/graemlins/smile.gif

 

[Scarron]

Our 1969 Sonny Levi designed Triana 25 has 25 Degrees of deadrise at the transom, designed in the mid sixties for the Cowes Torquay. The old ones are definately the best ---- Yeehah!

 

[Bajansailor]

Best for sea keeping would be a plank on edge, with 90 degree deadrise - no slamming, but a singular lack of stability and load carrying ability.

Best for load carrying and stability would be that plank floating norizontally (with sides added, ie a brick) - zero degrees deadrise, and singularly awful sea keeping.

Infinite choice of combinations anywhere in between to suit taste!

 

[PhilipF]

Not an expert on hull design - chose our Nimbus 280 for other reasons than that. Would be interested though in comments on the reasons for its handling in very rough seas: Last Wednesday, returning to Poole from Yarmouth, it was pretty calm in the Solent, but once past the Needles it became very rough - Force six to seven I would have thought.

Several times heavy waves badly nocked me off course, once as much as 140 degrees to port - always this side. Why? I'm a bit mysified. I suppose if the hull had a deeper 'vee' this should keep it straighter - would it? I was at all times hand steering. Would an autopilot help matters?

Also, regarding autopilots; is it worth going for the extra cost of a 'Rate Gyro'? This would add several hundred pounds to the £1500 including fitting of a Raymarine SI. Any other suggestions? We have a Simrad chartplotter.

 

[whisper]

How fast were you travelling ? It sounds as if you may have been going too slowly, hence the wave action could slew you around.
You may have felt it was not an option to speed up in such conditions, however.