Woods Skoota 32DM

[narfi]

I like the carbon look you did, looks really nice.

[cape man]

Very nice custom touch. Very nice.

[TomW1]

First what you have done looks really nice.

Fallguy up above you mentioned you purchased the Yamaha 90 Vmax SHO's, nice motors. The problem is the weight is 244lbs more than the planned 70's and you worry about a stern down problem. This is something I help guys with all the time. The formula is distance from LCG x added Weight. So LGC x 244lbs. = Z So let's do an example: First the measurement is taken at the base line to the motor. Then your boat is 32' long let's put the helm 18' from the motors, so 18 x 224 = 4032lbs. Now some how that 4032lbs must be redistributed forward of the LCG. This can be done by gas, water, anchor, chain and rope, cabinets, anything that is not part of the base boat. So any any weight moved forward x distance subtracts from the 4032lbs you need to move. Again this is an example.

So any way that is the calculations you need to make and how you go about them. A spread sheet works well.

You may have enough cabin weight forward that you don't need to do anything.

To

[fallguy1000]

First what you have done looks really nice.

Fallguy up above you mentioned you purchased the Yamaha 90 Vmax SHO's, nice motors. The problem is the weight is 244lbs more than the planned 70's and you worry about a stern down problem. This is something I help guys with all the time. The formula is distance from LCG x added Weight. So LGC x 244lbs. = Z So let's do an example: First the measurement is taken at the base line to the motor. Then your boat is 32' long let's put the helm 18' from the motors, so 18 x 224 = 4032lbs. Now some how that 4032lbs must be redistributed forward of the LCG. This can be done by gas, water, anchor, chain and rope, cabinets, anything that is not part of the base boat. So any any weight moved forward x distance subtracts from the 4032lbs you need to move. Again this is an example.

So any way that is the calculations you need to make and how you go about them. A spread sheet works well.

You may have enough cabin weight forward that you don't need to do anything.

To

At the moment (hehe), it will have to be a wait n see.

The boat's ppi is about 750#, so we may slop an inch astern. I had another NA tell me I might be light astern, but I think the boat will run high on the bow.

We might need some lead n resin in the forward lockers, but because this is a prototype boat, we must wait until she hits water. It is also semi-planing, so we need to use the level underway as well. Static level might end up bows down.

When you express those moments in pounds and not foot pounds, they are terrifying. Thankfully I understand.

The LCG is 4.869M aft of 0
The LCB is 5.978M aft of 0

I have always considered 0 to be dwl aftmost...should verify w/Richard.

Loaded waterline is 9,504M, Loaded OAL is 9.9m, but any resin n lead forward would be about 9.5M

The 244# weight added moment would be 3904 ft-lbs
The offfset would be 128 pounds of lead ne resin forward. But my cabin was built heavy and has solar and lots of stuff not in the load calcs. So it might wash out close and we might end up an inch low in the water. (Makes me sad after all the vac work).

The boats designed displacement is about 8800#.

The hulls weigh about 1600 no fuel or engines. Add about 800 for fuel and engines and 2400 per hull loaded is 4800.

The beams are about 350, cabin is around 4000, cockpit and aft beam 250. A guess puts us at 4600.

I expect the weight to be 9400. Have 53 gallon water tanks forward of lcg and to port as well, star is heavy near lcg. Anchor might even help.

Coulda saved 300# with non-mat tapes. But my work is really nice looking for it..

Water tanks getting filled might be enough. We'll see in April/May. The crane lift will give us lightship weight.

[BarraMan]

I’m surprised to see that you are putting “Vmax SHO” motors on that boat!

[fallguy1000]

I’m surprised to see that you are putting “Vmax SHO” motors on that boat!

How so?

[TomW1]

I was sort of surprised also. The only difference is the gear ratio 2.12 vs 2.33 between the two as far as I can tell. This allows it to increase the size the pitch of the prop and top speed of the boat. Some thing Fallguy doesn't really need. They are great motors but are best on a bass boat or similar.

Fallguy do you know what prop they put on your motors? Name, diameter, pitch.

Tom

[BarraMan]

I’m surprised to see that you are putting “Vmax SHO” motors on that boat!

How so?

As I understand it the SHO stands for Super High Output. My Vmax SHO just loves to turn gas into forward motion and noise - just not something I would equate with a Skoota 32 style of boat.

[OrangeQuest]

I would think the boat being a little heavier than designed, you would want the higher ratio to push a bigger prop to get the boat moving and keep it move without using more fuel and added strain on the motor. The comparison charts show the VMAX SHO getting best fuel consumption to MPH in the 4000 rpm range with the 2.33 gear ratio and the standard 90 hp at 3500 rpm. With only a .4 GPH difference but at a higher speed, by almost 5mph. So even though you are using more fuel per hour you will get there sooner, so in the long run use less fuel. But the motors are on different boats with different hull shapes so would be hard to compare without using them both on the same boat. Yamaha also states the VMAX SHO to be one of the quietest in it's class.

[BarraMan]

Yamaha also states the VMAX SHO to be one of the quietest in it's class.

The others “in its class” must make a hell of a racket then, cause mine is NOT quiet, by any stretch of the imagination - but man can it motor!