Bracket vs hull extension vs stretch????
 

Hi all,

I have been lurking here a good while and been soaking it in. I have a 20’ Seafari I am planning on starting a full teardown on soon (this was Otto’s 1970 i/o). My goal for the boat is a fishboat for Long Island Sound, not the biggest water, but sloppy water. I would like to have a closed transom and a fair bit of power (a light 140-150 hp). Low planing speed is important.

I understand how flotation brackets fit into the picture on these boats and the pros and cons. The question I have is what would the downsides be of extending the stringers and using the existing stringer system for support of a “bracket-like” extension rather than adding a bracket to a finished transom? If I have to “do” the transom and floor already it seems like the approach of extending the stringers and hull would be less weight in the end. I understand the time/effort/expense in all these approaches vs. adding a bracket. I’m looking for a project.

I can see three ways to go…

The first you could stretch the hull 2’ (or 2.5’) using the structure there and the original full transom would stay to become a false transom. I haven’t seen much talk of stretched 20’s, I know these hulls are long and narrow already. Thoughts?

In the second, you could extend just the hull center 2’ (or 2.5’) using all 4 stringers and hang the motor on the extension (see drawings). The extension could comprise the center and leave room for tabs outside. This would offer less flotation than stretching but more than a bracket since it would be deeper and displace more water (but would not offer the clean water/raised motor benefits of a bracket). Thoughts?

In the third case you could add an extension that duplicates a bracket by extending the stringers, but has a step in the hull as with a bracket (see drawings). This would exactly duplicate a bracket, but would probably weigh less without having the structure of a full transom with a bracket bolted on to it.

Original hull in blue, additions in red.

http://i638.photobucket.com/albums/u...r/Seacraft.jpg


These may not be original thoughts, but I haven’t seen them discussed. I can see some concerned with the aesthetics of modifying the structure and I appreciate that feeling, but I don’t see a whole lot of difference from bolting and 5200ing a bracket on. I’d also rather see an old girl used and abused than idle.

Thoughts? I’d love to hear them.

Tod

Re: Bracket vs hull extension vs stretch????
 

TDosier - It's a LOT more work to build out the transom and extend stringers vs. bolting on a bracket for very little reward. Center of gravity is a bit of an issue with a bracketed 20. One thing that helped me was removing the door and storing 128quart cooler full of ice and fish in the stepdown area. Tabs are an absolute must have with the bracket.

http://www.wellcraftv20.com/gallery/...Medium_001.jpg

Re: Bracket vs hull extension vs stretch????
 

You can do a hull extension bracket. I recently built a couple for RIBs. Build bracket/hull extension mold, build part with it's own stringers.Bolt on part with 5200 sealant then glass seams. Quick and easy. I have a slideshow on my website homepage that shows the finished products. :D I did not do the rest of the rebuild so the boats are still not complete and in the water but the 730 Willard RIB has been water tested with excellent results.

Re: Bracket vs hull extension vs stretch????
 

Big,

I know I'm talking a major effort vs buying a bracket, but... have any thoughts on the various options otherwise?

Tod

Re: Bracket vs hull extension vs stretch????
 

Thanks, I'll look up the slideshow, I hadn't thought of it that way.

Tod

Re: Bracket vs hull extension vs stretch????
 

If you extend the hull running surface, you will change the dynamic stability and how the boat planes. Not somethign you want to do unless you are able to calculate and predict the what your new hull will do. Raising the bracket slightly allows the water to break clean off the original planning surface (hull), but its there almost in an instant for displacement when you come off plane or a swell overtakes you.

AS far as making it yourself and tying it into the stringers. I gave this thought myself for my 23CC and I have seen it done before. Its a ton of extra work, but it is possible. I will go with a bracket for my boat, I would rather spend the time and energy on other parts of the boat.

Re: Bracket vs hull extension vs stretch????
 

Hi todosier

Over the years there has been some talk on this topic and project so fare I have not seen much regarding the actual project itself.

I have always kind of liked the concept but the practicality, the level of difficulty and the time and effort has always cause me to shy away from cutting up my boat as a experiment. I have always been a believer that the second mouse gets the cheese and the first mouse gets his head handed to him.

One of my practicality barriers is WHY would I want to make a 23 SeaCraft out of a 20 SeaCraft WHY not just buy a 23 and be dune with it??

As far a difficulty goes it’s a lot harder to extend a hull that to buy and attach a bracket from HermCo and his Brackets really look Sweet.

And then there is the time and effort. When I did my boat I worked slow but did a good job (for a armature) this would take lots of time and Lots of Beer.





FellowShip

………………………….

Just for the Grins :D :D

Official 23’ SF Antique Classic SeaCraft Owner

Re: Bracket vs hull extension vs stretch????
 

YIKES!!!!!......you seen the price of beer lately??

Re: Bracket vs hull extension vs stretch????
 

There is also a bit of a performance benefit to the bracket. Since the water want's to rise after it clears the transom, when you move the motor aft you can also raise it, at least one inch per foot of setback. Less lower unit in water = less drag, which translates to a little more top speed. I've seen reports that a bracket can be worth 2-3 mph.

Re: Bracket vs hull extension vs stretch????
 

Hull lengthening changes the hull rocker, which affect the angle of attack when coming on plane, planing and when falling off plane. With the VDH hull I would think you would positively have to have a pad or flat planing surface extended on the keel to enhance longitudinal stability, and lessen wetted surface drag. The alternative would be calculating hull rocker and building that into your extension.

Re: Bracket vs hull extension vs stretch????
 

Extending a hull is done quite often. On the Mako site there was a guy did one and I have read about several and done many myself. The most complex one I have done was a 28' Ocean Master into a 31' and then added a bracket. Not as hard as you might think. ;)

Re: Bracket vs hull extension vs stretch????
 

Mako hull extension,
web page

Re: Bracket vs hull extension vs stretch????
 

Yes thanks, I haven't measured rocker along the keel or any of the panels for that matter. My thinking without those measurements would be none as you said for the small amount of extension I'm talking. I would like to add an absolute minimum of length to get the flotation to support the motor. I'd add one foot if I could, but I have a full transom on the boat and I'd rather not cut it up to put a motor well in, since I like the rear of the i/o as is.

Re: Bracket vs hull extension vs stretch????
 

Thanks, I've read parts of the Mako post before, but haven't gotten through it - wow?!?!?

One question I have that you would 100% know is - what is the minimum amount of extension that can be added to get motor clearance with a bracket on an full transom? Your standard brackets are 30", is that for flotation or to give motor clearance? At what shortness do you have clearance problems? I'd like to build to fit all the current motors, but am planning on Zuke 140/Etec 150 because of weight.

Re: Bracket vs hull extension vs stretch????
 

Thanks Fellow-ship, I for sure don't want to stick my neck out too far! I'd like to add the bare minimum to get the flotation I'd need without creating more problems than I had.

If it hasn't been done that is news that I was looking for. I understand about going to the trouble to make a boat something it isn't and that isn't my intention. All things considerd, a 20' Seacraft is a perfect size boat for me and my needs, I wouldn't even consider a 23 for what I want to do. I've fallen in love with the lines and history of these boats and I want to get one on the the water and get as close to ideal (origional) performance with a modern motor. My thinking was that just a touch of extension to get the displacement needed would help the low planing speed that I think is important.

Re: Bracket vs hull extension vs stretch????
 

Thanks Denny, I'm not so worried about the high end performance gained, but the ability to slog it out against the slop in comfort. A motor in the 150 hp range will get me all the speed I need (except maybe on a really flat warm day :). I'm worried about slow planing speed.

On another note. the waterline on the I/O Seafari is truely amazing how deep it sat in the water with several hundred pounds of extra weight. I haven't ridden in one, but they must ride well with all that weight forward.

Tod

Re: Bracket vs hull extension vs stretch????
 

30 inches is for the big V-8's. I believe 27-28 for a zuke 140. Decide what kind of engine you want and then look up the specs for that motor in full tilted up position and then Bingo you have your minimum extension needed. Add another inch or two to be safe ;)

strick

Re: Bracket vs hull extension vs stretch????
 

;)

Re: Bracket vs hull extension vs stretch????
 

Todd, I've been a fanatic about low speed planing since day 1, and my rig will plane at 12-13 mph with full load (~3900 lbs total boat + crew load; will email you my weight summary) @ 2500 rpm, exactly what I want. Just ask Snookerd, GFS, Skip or Carla, who have all ridden on my boat in choppy conditions. What it takes is trim tabs, a 4-blade prop, and maybe a Doelfin or equivalent. (I added the fin before I tried a 4-blade prop. May have to take it off one day just to see if it makes any difference.)

Here's a couple photos that should answer the clearance issue. This first one shows fore & aft clearance with motor at full tilt.
http://i188.photobucket.com/albums/z...Tltpindist.jpg
This next one is a better shot of clearance with transom . . . about 7.5". http://i188.photobucket.com/albums/z...tclrncmeas.jpg
My bracket has a 30" setback. From this picture, I'd say a 24" setback would work fine for a 150 E-tec. Don said he could make them in 18, 24 and 30" sizes. If you went with a 115/130 V-4 E-Tec, you might even be able to use an 18" setback; you should be able find motor height difference between the V-6 and V-4 from BRP website or from this great E-Tec owners forum web page . Just looked at my 2009 catalog and it looks like they've gained weight since I bought mine, or else they've changed from quoting dry weight to wet weight. A 25" shaft 150 is now 433 lbs (mine was 427); a 25 115 is 390 lbs. I do know that BRP includes weight of the cowling. When you compare to a 4-stroke, make sure they include the weight of the oil and cowling!

Although I originally considered the 115,I've ended up so heavily loaded on some of my trips, I'm glad I went with the 150. Even with that load it gets on plane at less than half throttle! One other thing to consider is that the Seafari is a little less stern heavy than the CC's, so that makes motor weight a little less critical. Denny

Re: Bracket vs hull extension vs stretch????
 

Are those numbers available? I've looked online for them and haven't found them - that is why I asked.

I know they exist, but I haven't found them.

30 inches is a place to start from, but I'm not comfortable extending that far, given that no one has done it. I like the I/O cap a lot in the stern with the boxes, but I've measured and I think I could fit a well between them to accomodate the outboard in the up position if I could do a clean job that would fit with the lines of the boat. Extend the hull 18" (gives a couple hundred pounds of flotation if my quick math is good) with a well in the origional transom.

Re: Bracket vs hull extension vs stretch????
 

Todd - guess what I was trying to imply in my previous post is that you can achieve what you want (good ride and low planning speed) by just installing a Hermco Bracket; if you don't use boat for diving or run with real heavy loads, maybe with a shorter one with a 115 V-4. That's got to be a whole lot less work and $ than lengthening the boat! Denny

Re: Bracket vs hull extension vs stretch????
 

Denny,

I understood. Over the past year I've paid special attention to your comments regarding the bracket, especially since your have a Seafari with new power.

If the boat only needed new power, a bracket woudl make sense to me, but I'm starting from zero. This is on purpose, I like projects, I have the time and resources to get this boat back into shape exactly the way I want with all the doo-dads and additions I want and none I don't.

I'll have lots more questions, especially Seafari specific questions, so bear with me.

T

Re: Bracket vs hull extension vs stretch????
 

I would think a bracket, preferably a twin bracket would more than serve your purpose. Personally the commitment of time and money to lengthen a hull against adding an adequate bracket doesn't make sense. But that's just me.