18 or 21 degree deadrise

[DazSamFishing]

G'day,

I'll be outlaying some coin to purchase a custom made centre console from a QLD builder.

I'm after some opinions & commentry on the degree of deadrise. 1 hull having an 18 degree deadrise & the other @ 21 degrees.

LOA is 5.7m & the boat will be used predominently in offshore waters.

Appreciate any feedback on personal experience with a hull of similar or same deadrise. More importantly, will a 3 degree difference have any impact. The hull with the 18 degree deadrise is considerably cheaper than the 21. Although, both boats are built by very reputable plate boat builders.

Thanks.
Daz.

[TJ Bear]

There is a lot more to the performance of a hull than just the deadrise at the transom that make it impossible to give an opinion on how the boat will perform with just that information. Is the deadrisise variable? What is the deadrise at amidships, does the hull have a flat chine or or reverse chine? How wide is the chine and does it carry its width all the way forward? Does the hull have planning strakes and if so where are they located and what dimensions are they? Does the hull carry its volume forward with big shoulders or is it more of a carolina flare, what is the boats designed displacement? etc etc etc.

[TheRealAndy]

A bit of a generalisation here, but a sharper deadrise at the stern usually follows from a sharper entry deadrise. The more pointy it is, usually the better it is in choppy stuff. However, sharp deadrise also means more fuel consumption and slower onto the plane. Can also cause a lack of stability at rest.

Lower deadrise usually follows a less pointy bow. A flatter boat is usually easier to get onto the plane, is better on fuel and will be more stable at rest.

Just remember, this are not hard fast rules. Once you bring into play some of the stuff TJ Bear mention things do change. Talk to the builder and get their opinion too.

[DazSamFishing]

I'll be discussing the 2 boats with the 2 builders next week & will gather more information. I just don't like comparing 1 builders boat to another builders boat... You always seem to get bias information.

[DazSamFishing]

By comparing 2 boats - I mean dicussing & comparing with the boat builders, not the general boating public.

[White Pointer]

A bit of a generalisation here, but a sharper deadrise at the stern usually follows from a sharper entry deadrise. The more pointy it is, usually the better it is in choppy stuff. However, sharp deadrise also means more fuel consumption and slower onto the plane. Can also cause a lack of stability at rest.

Lower deadrise usually follows a less pointy bow. A flatter boat is usually easier to get onto the plane, is better on fuel and will be more stable at rest.

Just remember, this are not hard fast rules. Once you bring into play some of the stuff TJ Bear mention things do change. Talk to the builder and get their opinion too.

G'day,

Ditto this post. To overcome the stability at rest issue two boat builders use (used) ballast tubes. Fisher Boats Maxi series and Barcrusher. I can't remember the deadrise of the Barcrusher but the Fisher Maxi was 23 degrees and it cuts like a knife.

Regards,

White Pointer

[Smithy]

How come you're not getting a WA built boat if you are over there?

[Bowser]

Yeah there is a lot more to it then just the dead rise. Generalising it to the degrees only is just that, a generalisation. A flat hull will take a lot less power to get it to plane, as the V increase the boats ability to plane becomes less, power requirements grow as the wetted area increases. It really gets complicated. Then you introduce planing aids like strakes, chine flats, reverse chines and planing boards. The only way you will really be able to differentiate is to test ride each boat in a variety of conditions and decide which one suits you. This is all without talking about stability at rest. You need the chines to be under water a couple of inches at rest to stop it falling over.

To get any meaningful opinion you will have to name the boat builders, at least someone who owns one can then make a comment based on their experience. A I said to a mate this afternoon, all boating is a comprimise, whether it be ride, fuel economy, price, stability, fishability, shelter, cabin set up or cost, you will have to make a comprimise somewhere.

[FNQCairns]

What width is each boat? generally speaking 2 boats one with 18 the other 21 and both have the same waterline length and width the 21 will be miles in front in the rough stuff apples to apples.

cheers fnq

[siegfried]

There is a lot more to the performance of a hull than just the deadrise at the transom that make it impossible to give an opinion on how the boat will perform with just that information. Is the deadrisise variable? What is the deadrise at amidships, does the hull have a flat chine or or reverse chine? How wide is the chine and does it carry its width all the way forward? Does the hull have planning strakes and if so where are they located and what dimensions are they? Does the hull carry its volume forward with big shoulders or is it more of a carolina flare, what is the boats designed displacement? etc etc etc.
Exactly , 21deg however is not what you would class as a deep vee but I certainly wouldnt have any less get that with all the other factors TJ mentions and you will have all the fundamentals of a nice user friendly rig with a good compromise between stability and ride. Remember but a stable boat is nice but no good if you get the $&*t belted out of you, It is however a good way to deter wives /girlfriends etc from going boating all the time. Good luck

[DazSamFishing]

How come you're not getting a WA built boat if you are over there?

I'll most likely be back in QLD by the time the boat is built. If not, I'll use the boat in QLD before transporting it back to WA.

[DazSamFishing]

Yeah there is a lot more to it then just the dead rise. Generalising it to the degrees only is just that, a generalisation. A flat hull will take a lot less power to get it to plane, as the V increase the boats ability to plane becomes less, power requirements grow as the wetted area increases. It really gets complicated. Then you introduce planing aids like strakes, chine flats, reverse chines and planing boards. The only way you will really be able to differentiate is to test ride each boat in a variety of conditions and decide which one suits you. This is all without talking about stability at rest. You need the chines to be under water a couple of inches at rest to stop it falling over.

To get any meaningful opinion you will have to name the boat builders, at least someone who owns one can then make a comment based on their experience. A I said to a mate this afternoon, all boating is a comprimise, whether it be ride, fuel economy, price, stability, fishability, shelter, cabin set up or cost, you will have to make a comprimise somewhere.

Comparing a OMM 5.30 conventional centre console to a Blue Water 5.3 CC