(no title) - Page 6

PharmD2B31 · #51 10-12-2013, 05:12 PM

Built a roll around dolly for underneath the boat. Now I can move my boat in and out of the shop.

Sitting up on the dolly real nice and stabile. Threw the oversized 23' Seacraft console in it to see how it's going to look.

FishStretcher · #52 10-12-2013, 06:02 PM

You may find that there isn't room for vertical rod holders on at least one side of the console, otherwise it might be tough to squeeze by. I have a master angler with a slightly wider cap, and I had to remove the rod holders on the starboard side. If I ever unbolt the console, I will move it to the port side. An asymmetric look, but more practical for me. It might be a little bit easier on a regular Sport Fisherman.

RUSTYNTABATHA · #53 10-12-2013, 07:03 PM

very cool idea !!

PharmD2B31 · #54 10-12-2013, 07:45 PM

Quote:

Originally Posted by FishStretcher

You may find that there isn't room for vertical rod holders on at least one side of the console, otherwise it might be tough to squeeze by. I have a master angler with a slightly wider cap, and I had to remove the rod holders on the starboard side. If I ever unbolt the console, I will move it to the port side. An asymmetric look, but more practical for me. It might be a little bit easier on a regular Sport Fisherman.

There will be plenty of room on either side of this console because I am taking about 8" out of the middle of it to narrow it up. The dimensions on this console will be 49"L x 31" W x 44"H, similar to a console that Birdsall Marine makes. I like this console for the upward height it is compared to the console that came out if it.

When I am done, this console will be even more narrow than the one that came out of it.

PharmD2B31 · #55 10-19-2013, 05:51 PM

I have been looking around online at older model 20' Seacraft particularly the ones with the inboard/outboard set-up. I have been looking at these particular engines that have been put into these boats and they appear to be Mercruiser 135 hp inboards with the Bravo outdrives. The reason I have been looking at these set-ups is due to the weight of these particular engines.

I see all over this forum about keeping the engine as light as possible to balance out the boat and yet these inboard/outboard engine set-ups are WAY heavier than a single outboard engine.

If I am looking correctly, these inboard engines are weighing in at 700-1000 lbs, then add another 150 lbs for the outdrive????

If this is the case, I am thinking about maybe trying to put a Yamaha F300 on my 20' Seacraft. I dont see why it cant be done since I have seen the new F200 on the back of one and the F300 is only 73lbs heavier at 562 lbs.....which is also WAY lighter than those inboard/outboard set-ups.

Again, I dont know why it cant be done since there are many other boat manufacturers out there that are building same size footage boats (bay boats) and sticking larger engines on them with no problems.

I'd like to hear others comments on this........

Bushwacker · #56 10-19-2013, 08:13 PM

You're ignoring a key factor in the CG equation! It's not only the absolute weight that's important, it's WHERE it's located, that determines the boat's CG location! The weight of that 4 cyl engine (I think your I/O weight numbers are about right) is probably centered at least 12-18" forward of the transom, while the weight of an outboard will be centered 6-12" AFT of the transom!

I specifically asked Carl Moesly how the overall CG location compared on the I/O's vs. the outboards on the 20' Seafari. He said the CG is further forward on the I/O's, and this is in comparison to the outboard he designed the 19/20' hulls for, the I-6 Merc, which weighed less than 300 lbs! So how does that CG difference affect the performance of the boat? Here's a couple of examples:

CSC member Tiny had an I/O Seafari and sold it after he bought Fr. Frank's OB Seafari with the 90 hp Optimax, which weighs 375 lbs. He said the I/O model rode noticeably flatter and softer than the OB model; I went for a ride in the I/O boat and confirmed that it planed at 12 mph WITHOUT trim tabs! My Seafari would do that with a 300 lb outboard and WITH trim tabs. When I installed a 30" bracket with a 427 lb motor on it, my min planing speed jumped to the low 20's! This was totally unacceptable for offshore use because the 20' hull is relatively light and starts to go airborne over 20 mph in seas of about 3'! In those conditions, you can't even use 150 hp, let alone 200 or 300! I had to add a Doelfin and 4B prop, both of which reduce top speed, to get my min planing speed back down to 12 mph!

Also you should know that those quoted 4 stroke weights are DRY weight! Once you put a couple gallons of oil the crankcase, lower unit and tilt/trim system, I'm pretty sure that F300 will weigh over 600 lbs! The motor weight issue on the 20' hull has been discussed many times on here, and the consensus of the experienced guys is that it's a very efficient hull designed for lightweight motors, so lighter is better especially for a good ride, and around 400 lbs is about the heaviest you want to go for best all around performance! The Seafari has more weight forward so can handle a heavy motor better than the CC's, but you can compensate, up to a point, by moving the console, gas tank and batteries forward to help balance a heavy motor.

gofastsandman · #57 10-19-2013, 08:37 PM

And your boat touches 50 light.

PharmD2B31 · #58 10-19-2013, 09:04 PM

I am merely funning about the Yamaha F300.......would be cool and I know it CAN be done as there was just a Mercury 275hp.....but where or not it would be the ideal set-up is clearly another issue.

So does anyone have the center of gravity numbers for a 20' Seacraft Center Console??? I have been reading up a good bit on center of gravity on boat building. To my understanding most boat center of gravity is about 60-65% of the total length of the boat from the bow.

If that is the case, then that would put the center of gravity for the boat at 11.7-12.7" measuring from the bow of the boat back. And this is just with the hull only.

If we were to add a bracket, I was wondering if you had to figure the bracket length into the total length of the boat......going from 19' 6" to 21' 6" if we were to add a 24" setback bracket???? This would move the center of gravity for the boat back 1-2" to 13-14' measuring from the bow of the boat.

I may be totally WAY off on all of this.......that is why I am asking as maybe someone else ACTUALLY knows the answer.

When building my boat back, I am wanting to make sure that I am keeping the boat as balanced as possibly and not just going off guestimations.

I know if I can calculate the center of gravity for the boat I can then apply foot pounds of downward force applied to the boat with however my boat is going to be set-up and optimize the center of gravity of the boat on weight distribution.

Mikem8560 · #59 10-19-2013, 09:33 PM

ive got a 200 merc just over 400 pounds I have 4 batteries in the console at reast the scuppers are dry till I walk to the very back but for the most part only the channel is wet

Blue_Heron · #60 10-19-2013, 09:49 PM

Quote:

Originally Posted by PharmD2B31

I am merely funning about the Yamaha F300.......would be cool and I know it CAN be done as there was just a Mercury 275hp.....but where or not it would be the ideal set-up is clearly another issue.

Good.

You scared me.

Quote:

Originally Posted by PharmD2B31

To my understanding most boat center of gravity is about 60-65% of the total length of the boat from the bow.

I believe the CG of planing hulls is normally measured from the transom heel (the point where the keel intersects the transom). It is usually measured as a percentage of static wetted length.

The static wetted length of a 20' Seacraft is about 17.5'. I've been told that a typical CG should be at about 33% of static wetted length, which would put the 20' Seacraft CG about 5'-9" forward of the transom heel. This is not gospel, just some preliminary calcs I've done preparing for my own 20' resto.
Dave