Blow Out

[Fletch170]

I was on THT, reminding myself why I don't belong to that "online community" and I came across an article stating that they had a "blow out" on a 36 Yellowfin.

This is something I never heard before. Can someone explain? Is it something where your motor/motors lose bite and the boat slides on the hull sides? I'm just trying to visually understand what the heck actually happens.

[seabob4]

"Blow Out" typically refers to a prop loosing grip, common on multiple engine boats when turning at relatively high speeds.  Not very common on singles where the engine is centered on the keel, which stays well planted in the water during turns.

[Fletch170]

I guess when you are running a $300K beer cooler down the intercoastal at 70 MPH, these things can happen.....


So does the ass end whip around? Causing a pitchpoil type situation?

[seabob4]

Not really.  You notice an almost instant loss of speed coupled with the corresponding tach REALLY jumping up in RPM.  Chopping he throttles pretty much settles things down...

Unless someone is a professional driver, high speed turns are not a good thing.  Before the turn, trim in to put more hull in the water and reduce speed, then make the turn.  Apon exit, resume normal CRAZY SPEED operation!!    

[Fletch170]

I just don't understand trips on a 36 foot boat. I mean, what do you get out of it vs twins? 6MPH?

[fitz73222]

Technically blow out is loss of prop bite created by a bubble that forms on the front of the gearcase and migrates into the prop area. It is the reason why that racing or high speed gearcases capable of 90+ mph have the extended nose, so this void created by the gearcase has time to collapse before it gets into the blade area. I have experienced blow out in an Allison XTB its almost like you turn the key off at 85 mph and when the hull comes off of the pad at that speed, they usually go sideways. So basically you lose all control and try to keep her from rolling on top of you. This is usually a go fast boat problem; I'm thinking the guy had a ventilation problem and not blow out; but I learn something new everyday.

[seabob4]

I would agree with fitz, more ventilation than blow out.  As he said, look at gearcases such as speedmasters, #6s, etc.  Low profile, elongated, very sharp point of entry...

[wingtime]

kinda like this:

[seabob4]

kinda like this:

And throw a 5 blade cleaver prop on the shaft...  

[Capt. Bob]

I'm thinking the guy had a ventilation problem and not blow out; but I learn something new everyday.

This is interesting that this comes up.

It was what I was referring to when, on another thread, motor mounting height was discussed. The Factory may recommend a lower mounting height for a liability issue rather than a 'blown motor" issue.
No, most don't own "go fast" hulls, then again most aren't pro drivers so...

A little wiggle in a turn caused by a motor mounted a little too high could lead to over-correction and possible injury (now think lawsuit) by a weekend boater and the slip and fall crowd. One good settlement could easily surpass the costs of a box car load of blown motors. I know which one I'd be guarding against.

It's just the way I think about anything now a days.

[Fletch170]

Here is the thread I was talking about:

http://www.thehulltruth.com/boating-for ... cible.html


I personally think the whole center console performance market has gone batsh!t crazy. All these guys downsizing from large sportfish boats, but still need to show off how much expenable income they can throw into the water, end up with 1050 HP 36 foot boats. Let's add a step or two into the hull, that should make a bad situation worse. Mind you, it's not like these guys have any formal race training. IT'S A FISHING BOAT, WTF?

I've had the privlidge of running a lot of these high performance boats, and I love the performance side. However, there is a difference between making a boat perform well with economy and fishability, in comparison to just putting the most HP on the back of your quarter-million dollar di*k extension you fish on 2 times a year.

With that being said, I have a 17 aquasport.......whats up ladies!????

I don't care how great a boat rides, when the seas get choppy, you can only go so fast before you s*it out your fillings. So what's the point? A Yamaha 350 is roughly 25k.......that buys a ton of Fuel, Bait, Beer, Viagra, kids college,  whatever. Isn't the point of being on a boat to relax? If you're chine walking down the intercoastal at 85MPH, wondering if you dig a rail and spend the next 3 seconds relocating my teeth and anus to various points of my boat.......how is that relaxing?

I'm only 31, but I guess I sound pretty old at this point but seriously, I think this whole tripple/ quad nonsense is the product of having more bucks than brains.

Anyone else agree?

[fitz73222]

Since I will never have anything close to the disposible income required to spend $350K on one of these boats; I guess I will remain humble and proud of the fact that I have more people with those type of vessels asking me about my old 22-2 when its on the water than the opposite. The market will go where it needs to go to support demand. I too, am over the quad outboard, testosterone rides. But I remember the very beginning of this market in the late 60's and early 70's when it was quite pish posh to have one of our boats new. Spending $10,000 on a boat in 1972 was serious bucks reserved for the doctor and lawyer crowd.

[slvrlng]

Since I will never have anything close to the disposible income required to spend $350K on one of these boats; I guess I will remain humble and proud of the fact that I have more people with those type of vessels asking me about my old 22-2 when its on the water than the opposite. The market will go where it needs to go to support demand. I too, am over the quad outboard, testosterone rides. But I remember the very beginning of this market in the late 60's and early 70's when it was quite pish posh to have one of our boats new. Spending $10,000 on a boat in 1972 was serious bucks reserved for the doctor and lawyer crowd.

X2  That is the coolest thing when somebody asks you about your ride.

[Capt Matt]

Gotta get out to the Kingfish fast if you want to win the big money. Being able to be 60 miles out grouper fishing in a hour also kinda makes sense to me. Being able to run the 100nm to key west from here for lunch does sound like fun too. $100 lunch, $1000 plus in fuel to get there.  Or how about a day trip to fish the Dry Tortugas or a quick run out to the middle grounds?
A 24 yellowfin bay boat with a 350 v-rod would be my guide boat if cash was no object.
Not really much difference between a 36YF with triple motors and a 20ft lake and bay flats boat with a 300 pro xs, just a smoother ride on the YF.
Capt Matt