Dorado 30 High speed stability

[tonipu]

hi, i see a litlte beet keel in the bow if i noticed well, maybe 2inch deep, when my friend added a little bit keel to a fjord 25, it becomes a very unstable boat, and heve a big tendency to broaching, sometimes when we encounter a small wave, the boat go to one side and we must slowe down.
then he cut again the little keel he added, and the boat became stable again.
the keel was only 1 inch starting from the bow in the front, and maybe 4 inch on the aft

 

[tonipu]

Keel photo, he added because of low speed fishing, and it was better for low speed troling

 

[Mr Efficiency]

tonipu, it is a bit surprising that addition you pictured, would tend to broaching, you'd think it would be neutral at worst. Unless it isn't quite what he added ?

 

[tonipu]

Yes he add the small keel, the boat was incotrolable in litle folowing sea.
Tomorow i Will picture the boat, now original without keel

 

[tonipu]

As i promise picture of a keel he add on his fjord, an picture of the boat now when keel was removed

 

[Austin]

Just updating the thread.

still have the same results. The boat handles best at speeds under 28mph. It will run faster but requires a lot of steering input and constant attention.

Not really surprised as the boat was designed with a 200hp inboard diesel. Having 400hp is just overkill.

 

[Austin]

Another update. I filled the fuel tank which is close to 220 gallons and the boat rides handles much better at speed. It was able to cruise 35mph in 1 foot chop with a quartering wind with no issues.

I’m assuming the added weight low in the hull lowered the CG and puts more of the hull in the water moving the Center of Pressure (not sure that is called for a boat hull) to a better spot.

the boat drafts a little bit more but I will be keeping the tank full from now on.

thanks for all the help.

 

[Mr Efficiency]

That is a monster tank, it has probably put more forward portions of the boat in the water consistently, and presenting a different "face" to the water. Pleasing to get at least an improvement, good luck with it.

 

[sailhand]

My two cents worth is get rid of the ridiculous pod and extend the hull aft continuing the existing hull lines. The motors are some distance behind the transom and as you increase speed you have less hull in the water and its towards the aft end of the hull. This effectively creates a pivot point with the aft end of the boat. Having the motors well aft of this and without adequate bouyancy at speed you are really upsetting things. Any slight change in directional thrust will be magnified by your current arrangement. Very simple mod and would make a huge difference in my opinion. Dont forget my opinion is only worth two cents though.