Pushing the Estuary

[Davey W]

So with my replacement 15hp mercury motor, I noticed a difference in power from the doomed-from-the-start previous motor. I still bought a new prop, the Solas high thrust 4 blade in 10x7. Without a tach, I can still notice a huge difference in RPMs from the motor. The solas prop turns higher rpms. On new mercurys, they have an rpm limiter and the solas prop doesnt hit the limiter wide open, but the motor doesn't sound like its under such a load anymore. Rpm test is coming soon and then I'll know exactly what she turns.

The task at hand is still finding the optimum power, pitch and trim setting for pushing this fat heavy boat. The boat is a dream to hunt from and I wouldn't trade it, but either the motor angle or hull design still pushes the bow up high. Being that this is a boat website, do displacement hull boats always run bow high? Is this just the physics of the hull when pushes with power? By shifting all weight forward and running on a lower pin setting, I can get the bow to come down to the point where the motor sounds relieved of the load, which is what I want. Not trying to plane here guys, but what attitude should I expect the hull to run at when pushed at its optimum hull speed?

 

[Davey W]

Let me just add that I used to run the 44'MLB in the Coast Guard, which was a true displacement hull boat. Running wide open, the 44'MLB didn't have a drastic bow up attitude. I would like the Estuary to run level or close to level when wide open. It seems as though it would save my motor from literally pushing a 1' bow wake.

 

[tod osier]

For a short boat like that hull speed is in the range of 5 knots (you could calculate it, but I'm in the ballpark). If you want to go faster you are exceeding hull speed and planing. Planing poorly, but planing none the less - that is the bow up to the sky attitude.

 

[Davey W]

For a short boat like that hull speed is in the range of 5 knots (you could calculate it, but I'm in the ballpark). If you want to go faster you are exceeding hull speed and planing. Planing poorly, but planing none the less - that is the bow up to the sky attitude.

If its a 5kt hull, why is it USCG rated for a 15hp outboard?

 

[tod osier]

For a short boat like that hull speed is in the range of 5 knots (you could calculate it, but I'm in the ballpark). If you want to go faster you are exceeding hull speed and planing. Planing poorly, but planing none the less - that is the bow up to the sky attitude.

If its a 5kt hull, why is it USCG rated for a 15hp outboard?

It is a 5 knot hull at hull speed. Do some reading up on the physics of a displacement hull and see for yourself. There is a limit for a displacement hull in displacement mode, but it isn't magic you can push them faster than that, but you loose the efficiency and make them plane out (even if sloppily).

People commonly exceed hull speed with sneakboxes and enter planing mode.

Why a 15 hp? Because people like to go faster than hull speed.

T

 

[Larry J]

Davey,

have you tried a whale tail on the motor. I've seen many displacement hull sneak boxes with fins on their motors to try and solve the very issue you have. I believe the answer though is, the boat just wasn't meant to go that fast.

and on a lighter note.

http://www.youtube.com/watch?NR=1&v=lbDT0yotbPg&feature=fvwp [url]

 

[Howard]

Davey, the USCG horse power rating is a mathmatical calculation involving the length of the boat, width(and sometimes the heigth) of the transom and the style of the bottom. Doesn't really have a lot to do with speed, the idea is to not sink the boat.

 

[Davey W]

Thanks guys...like I said, its NOT about speed, but getting better performance from the outboard.

 

[Bob B]

Is this a David Clark Estuary?
I think it sounds like you have the hull sitting on the wave just past the displacement speed.
If that is the case the Fin for the outboard will help lift the stern. But they get in the way a lot. Try one and see if it helps.

I have never seen the bottom of the boat but I thought Dave set it up to run flat with a lot less rocker in the stern.

Bob

 

[Davey W]

Is this a David Clark Estuary?
I think it sounds like you have the hull sitting on the wave just past the displacement speed.
If that is the case the Fin for the outboard will help lift the stern. But they get in the way a lot. Try one and see if it helps.

I have never seen the bottom of the boat but I thought Dave set it up to run flat with a lot less rocker in the stern.

Bob

I think the hull originated from a layout boat design right? Its an incredibly safe, stable and sea worthy platform, but it just doesnt seem to like being pushed above idle speed lol. I'll get it running nice, just need to find the right combo. May try a fin.

 

[Dave Diefenderfer]

Davey, have you called Dave Clark? He built around 50 of these, he can tell you how to set up your motor and what you will get... you could be spending time and money that has already been figured out?

 

[tod osier]

Is this a David Clark Estuary?
I think it sounds like you have the hull sitting on the wave just past the displacement speed.
If that is the case the Fin for the outboard will help lift the stern. But they get in the way a lot. Try one and see if it helps.

I have never seen the bottom of the boat but I thought Dave set it up to run flat with a lot less rocker in the stern.

Bob

I think the hull originated from a layout boat design right? Its an incredibly safe, stable and sea worthy platform, but it just doesnt seem to like being pushed above idle speed lol. I'll get it running nice, just need to find the right combo. May try a fin.

That idle speed is hull speed.

 

[Ryan Werden]

Davey,

I have an Estuary which is powered by a 15hp Yamaha 2stroke. I too played around quite a bit with trying to push the bow down, not necessarily to gain speed, but to see if I could get it down enough so that I could sit on the deck while underway. When I first got the boat I was not very comfortable with standing. After spending some time in the boat I became much more comfortable with this concept. Anyway, I spoke to other estuary owners and realized that I’m trying to make the boat do something that it’s just not designed to do. I have found the sweet spot for me which is to take the motor to full throttle and then back off about a 1/4 turn. With a fully loaded boat I’m usually around 12mph and the attitude of the bow is where it should be. At full throttle I can squeak out a couple more mph but I don't like to run it flat out like that and for me, it's not worth the minimal increase in speed. I haven't noticed any material change in bow attitude either.

There are a couple folks who have tried 25hp motors and I believe they all went back to the 15 because there wasn't any gain in performance to justify all the additional weight.

The net/net is these boats are pigs in the water. They have a lot of rocker and anything short of idle, that bow is going to pop up. IMO, I think you will spend $/time in something that will yield little fruit.

Good luck.

Ryan

 

[Davey W]

That idle speed is hull speed.

Tod, maybe hull speed is zero. Maybe its not even a boat!

Ryan, thanks for chiming in. I wanted to hear from other Estuary owners. I think I'm just going to leave it as is. The new prop works great and I love the boat. Just have to get used to how the boat pushes.

 

[Gary March]

Good morning Davey
I have never really experienced what you are going through. From the very beginning of owning my Estuary I realized the boat was not a plaining hull and didn't expect to get much speed out of her. At my age speed is just not a concern. I started with a 25 2stroke only because that was a motor I had setting around. And one thing David Clark told me about the Estuary was in heavy winds and big water make sure you run with full power. I have listen to his experienced boatmanship and he was so right. I shortly took off the 25hp and purchased a new Mercury 15hp four stroke. Nothing changed on the way the boat ran as my normal cruising speed is about 8 knots. One day on a cold winter day I was on the columbia river in winds with guests to 50 mph. The boat was slightly overloaded and it performed impeccable for me. I at that time used maximum full throttle and yes, the bow was up higher than cruising speed , but thats where I wanted it. On another winter day in December I was hunting on the PendOreille River with steady winds to 55mph. Again the boat was slightly over loaded, because I think I need every decoy in the barn and a chubby water spaniel was with me.HeHe The boat again handled it very well and never did I feel any worries about being out there. As I continued to hunt out of the Estuary, it has become an extension of me. I am so comfortable standing while running it. I, at this time can't imagine owning any other boat, and believe me I have had my share. Just remember to use all your power if in high winds and big tides. On both of the days I was referring to I never had even a splash of water get inside my boat. Be safe out there and start a bit earlier. You to, will end up loving your Estuary. I hope this helps.

Gary March

 

[Craig F]

As others have mentioned you have to remember that boat was designed to handle big water in a small package, hence why having the bow ride high is a good thing, just pushing through the waves. It is a trade off, you could have a speed box design like the higbees, highlands boxes and the like and be able to scream out to your spot, but only when it is relatively flat.

So many people seem to come on this site looking for more speed out of their displacement style sneakboxes, putting wedges, dolefins, etc. but it is basically trying to turn it into something it is not. I have no idea what speed my box runs at, but it is plenty fast for me and I've hunted big water when larger boats haven't gone out. Safety is really the number one goal. If you start putting bigger engines, etc. onto a boat that is already heavy to begin with it isn't going to do anything but help give you a sore back moving it on and off the sedge.

 

[Anthony A]

As an Estuary owner, I second (or third?) what Ryan and Gary have written.

Lucky for me, it is my first ever boat, so I never had anything faster to compare it to! I get to my spot safer, and faster than if I would have paddled (which is what I was doing before buying the boat).

Love the boat to bits. Enjoy.

Sincerely

Anthony

 

[tod osier]

That idle speed is hull speed.

Tod, maybe hull speed is zero. Maybe its not even a boat!

Ryan, thanks for chiming in. I wanted to hear from other Estuary owners. I think I'm just going to leave it as is. The new prop works great and I love the boat. Just have to get used to how the boat pushes.

Davey, As I said hull speed is about 5 knots (less, actually) and yes, I would not be surprised if your 15 hp merc pushes it close to or at hull speed at idle.

 

[Davey W]

Thanks again for all those chiming in. I used to own a small planing hull box, and Jim D can attest, I was kind of nuts with that boat. It did 30+ mph wide open with a 15hp on it. So its a slight adjustment going to the Estuary, but I wanted a boat big enough for me and my dog and all the gear I bring and I wanted to stay warm and be safe in all weather conditions. I love the Estuary, I just didn't want to be running the motor with such a tremendous load in it, which the 4 blade prop helped to unload the motor. She runs 12mph at 3/4 throttle, which is what I'll run at most times. The extra power doesn't equate to much speed, wide open it runs 12.5-13mph.